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  • How to improve Minecraft-esque voxel world performance?

    - by SomeXnaChump
    After playing Minecraft I marveled a bit at its large worlds but at the same time I found them extremely slow to navigate, even with a quad core and meaty graphics card. Now I assume Minecraft is fairly slow because: A) It's written in Java, and as most of the spatial partitioning and memory management activities happen in there, it would naturally be slower than a native C++ version. B) It doesn't partition its world very well. I could be wrong on both assumptions; however it got me thinking about the best way to manage large voxel worlds. As it is a true 3D world, where a block can exist in any part of the world, it is basically a big 3D array [x][y][z], where each block in the world has a type (i.e BlockType.Empty = 0, BlockType.Dirt = 1 etc.) Now, I am assuming to make this sort of world perform well you would need to: A) Use a tree of some variety (oct/kd/bsp) to split all the cubes out; it seems like an oct/kd would be the better option as you can just partition on a per cube level not a per triangle level. B) Use some algorithm to work out which blocks can currently be seen, as blocks closer to the user could obfuscate the blocks behind, making it pointless to render them. C) Keep the block object themselves lightweight, so it is quick to add and remove them from the trees. I guess there is no right answer to this, but I would be interested to see peoples' opinions on the subject. How would you improve performance in a large voxel-based world?

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  • How to manage many mobile device users at server side?

    - by Rami
    I built a social Android application in which users can see other users around them by GPS location. At the beginning thing went well as I had low number of users, but now that I have increasing number of users (about 1500 +100 every day) it has revealed a major problem in my design. In my Google App Engine servlet I have static HashMap that holds all the users profiles objects, currently 1500 and this number will increase as more users register. Why I'm doing it? Every user that requests for the users around him compares his GPS with other users and checks if they are in his 10km radius. This happens every five minutes on average. Consequently, I can't get the users from db every time because GAE read/write operation quota will tear me apart. The problem with this design is? As the number of users increases, the Hashmap turns to null every 4-6 hours, I think that this time is getting shorter, but I'm not sure. I'm fixing this by reloading the users from the db every time I detect that it becomes null, but this causes DOS to my users for 30 sec, so I'm looking for better solution. I'm guessing that it happens because the size of the hashmap. Am I right? I have been advised to use a spatial database, but that means that I can't work with GAE any more and it means that I need to build my big server all over again and lose my existing DB. Is there something I can do with the existing tools? Thanks.

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  • Efficient path-finding in free space

    - by DeadMG
    I've got a game situated in space, and I'd like to issue movement orders, which requires pathfinding. Now, it's my understanding that A* and such mostly apply to trees, and not empty space which does not have pathfinding nodes. I have some obstacles, which are currently expressed as fixed AABBs- that is, there is no unbounded "terrain" obstacle. In addition, I expect most obstacles to be reasonably approximable as cubes or spheres. So I've been thinking of applying a much simpler pathfinding algorithm- that is, simply cast a ray from the current position to the target position, and then I can get a list of obstacles using spatial partitioning relatively quickly. What I'm not so sure about is how to determine the part where the ordered unit manoeuvres around the obstacles. What I've been thinking so far is that I will simply use potential fields- that is, all units will feel a strong repulsive force away from each other and a moderate force towards the desired point. This also has the advantage that to issue group orders, I can simply order a mid-level force towards another entity. But this obviously won't achieve the optimal solution. Will potential fields achieve a reasonable approximation given my parameters, or do I need another solution?

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  • 25 years old and considering a career change...possible? practical?

    - by mq330
    Hi all, I'm new to this site and new to programming as well. I've spent some time going through an intro cs book that uses python as the language of choice. I find the exercises interesting and engaging and I generally have had a favorable experience programming so far. I've gone through some of the basics with python like writing simple programs, basics of GUIs, manipulating strings, lists, defining functions, etc. And I've always loved technology. Although I've never done any real hardcore programming yet, I was inclined to building websites from a very young age but I never really developed my skills. Now, the thing is I'm 25, I have my bacholors in environmental studies and two masters degrees in urban planning and landscape architecture respectively. I know, it would be quite a departure to pursue a career in programming at this point. Currently, I'm working as a geographic information systems intern. I've taken some GIS classes and have a lot of experience with making maps, doing spatial analysis etc. So what I'm thinking is maybe I can learn some solid programming skills and apply these skills in the field of GIS. From what I've seen, .net languages are the norm in this arena. Could you perhaps provide some guidance to me in terms of what languages I should focus on or courses I should take at this point? What about for building web mapping applications? Also, I was thinking about getting a certificate in programming from a university extension program. Do you think it would be worth it? And furthermore, do you think potential employers would be interested in hiring someone like me (once I get a couple of languages down pretty well) as an intern or in an entry level position? I'll be living in the bay area so I feel that there should be decent opportunities even though I don't have a b.s. in cs.

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  • What is the best way to manage large 3d worlds (i.e minecraft style)?

    - by SomeXnaChump
    After playing minecraft I was marvelling a bit at their large worlds but at the same time finding it extremely slow to navigate, even with a quad core and meaty graphics card. Now I assume its fairly slow because: A) Its written in Java, and as most of the actual spatial partitioning and other memory management activities happen in there it would be slower than a native C++ version. B) They are not partitioning their world very well I could be wrong on both assumptions, however it got me thinking about the best way to manage large worlds. As it is more of a true 3d world, where a block can exist in any part of the world, it is basically a big 3d array [x][y][z], where each block in the world has a type (i.e BlockType.Empty = 0, BlockType.Dirt = 1 etc). Now I am assuming to make this sort of world performant you would need to: a) Use a tree of some variety (oct/kd/bsp) to split all the cubes out, it seems like an oct/kd would be the better option as you can just partition on a per cube level not a per triangle level. b) Use some algorithm to work out if the blocks within the scene can currently be seen, as blocks closer to the user could obfuscate the blocks behind, making it pointless to render them. c) Keep the block object themselves lightweight, so it is quick to add and remove them from the trees I guess there is no right answer to this, but I would be interested to see peoples opinions on the subject.

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  • Oracle Open World 2012?????

    - by Liu Maclean(???)
    Oracle Open World 2012?????: ???.. Oracle OpenWorld 2012 sessions????:Search Content Catalog for Oracle OpenWorld 2012 sessions ?????????session??? Open World 2012??: Larry ??Exadata X3 OOW 2012???Exadata X3,?? X3-2 ?Expansion Rack X3-2?X3-8 Exadata X3????:http://www.oracle.com/us/products/database/exadata/overview/index.html  ORACLE EXADATA Database MACHINE X3-8 sheetORACLE EXADATA Database MACHINE X3-2 sheet Exadata X3-2???????: X3-2?compute db node?????????8?Intel Xeon E5-2690??? ??????????12????16?,???33%????? ???96GB???128GB,????256GB ??????????50% X3-2 cell node??????????????Intel Xeon ??????flash card flash card??????4?,??flash card?????????40%? ???X3-2???22.4TB?flash ,??????flash????????????????????,???10????? CPU???6?,????????Intel Xeon model ????????X2-2??,???600GB???????3TB?????? ??Exadata X3-2?????????,??????????1/4?????,1/8????????????????? Exadata X3-8???????: X3-8???X2-8?????,???X3-8??????????X3-2??,??X3-8?????22.4TB?????? ???CEO??  Engineered to Work Together OOW????? Oracle Open World 2012 ????? Open World 2012 ??:http://www.oracle.com/openworld/index.htmlOpen World 2012 ????:http://www.oracle.com/openworld/register/packages/index.html ??: Sept. 30 – Oct. 4, 2012 9?30?? 10?4? ??:Moscone Center, San Francisco (747 Howard Street, San Francisco, California 94103). ?????Mark Hurd??OOW 2012: How big is oow OOW 2012?????????: Focus On Database Technologies Focus On Real Application Clusters Focus On Exadata Focus On Oracle Database Appliance Focus On Oracle Database Application Development Focus On Oracle Database Security Focus On Big Data Focus On Data Warehousing Focus On High Availability Focus On Oracle Enterprise Manager Cloud Control 12c (and Private Cloud) Focus On Oracle Spatial and Graph Focus On Oracle Database Utilities Focus On Oracle Database Upgrade Focus On Oracle Database Private Cloud Focus On .Net Focus On Oracle Database on Windows Focus On Engineered Systems Focus On Sunday Users Forum

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  • MYSQL Fast Insert dependent on flag from a seperate table

    - by Stuart P
    Hi all. For work I'm dealing with a large database (160 million + rows a year, 10 years of data) and have a quandary; A large percentage of the data we upload is null data and I'd like to stop it from being uploaded. The data in question is spatial in nature, so I have one table like so: idLocations (Auto-increment int, PK) X (float) Y (foat) Alwaysignore (Bool) Which is used as a reference in a second table like so: idLocations (Int, PK, "FK") idDates (Int, PK, "FK") DATA1 (float) DATA2 (float) ... DATA7 (float) So, Ideally I'd like to find a method where I can do something like: INSERT INTO tblData(idLocations, idDates, DATA1, ..., DATA7) VALUES (...), ..., (...) WHERE VALUES(idLocations) NOT LIKE (SELECT FROM tblLocation WHERE alwaysignore=TRUE ON DUPLICATE KEY UPDATE DATA1=VALUES(DATA1) So, for my large batch of input data (250 values in a block), ignore the inserts where the idLocations matches an idLocations values flagged with alwaysignore. Anyone have any suggestions? Cheers. -Stuart Other details: Running MySQL on a semi-dedicated machine, MyISAM engine for the tables.

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  • Windows Azure Platform, latest version?

    - by Vimvq1987
    I searched through internet but found nothing. The whitepapers of Windows Azure Platform say something like that: In its first release, the maximum size of a single database in SQL Azure Database is 10 gigabytes A few things are omitted in the technology’s first release, however, such as the SQL Common Language Runtime (CLR) and support for spatial data. (Microsoft says that both will be available in a future version.) I want to know that Microsoft had updated Windows Azure Platform and removed these limits or not? I decided to post this question here instead of Serverfault.com because it's more relative to programming than administration. Thank you

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  • AS3: How to access pixel data efficiently?

    - by JonoRR
    I'm working a game. The game requires entities to analyse an image and head towards pixels with specific properties (high red channel, etc.) I've looked into Pixel Bender, but this only seems useful for writing new colors to the image. At the moment, even at a low resolution (200x200) just one entity scanning the image slows to 1-2 Frames/second. I'm embedding the image and instance it as a Bitmap as a child of the stage. The 1-2 FPS situation is using BitmapData.getPixel() (on each pixel) with a distance calculation beforehand. I'm wondering if there's any way I can do this more efficiently... My first thought was some sort of spatial partioning coupled with splitting the image up into many smaller pieces. I also feel like Pixel Bender should be able to help somehow, however I've had little experience with it. Cheers for any help. Jonathan

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  • Problem creating PostGIS template database

    - by omat
    I am trying to build a template geographic database for PostGIS (1.5) on Mac OS X Snow Leopard (10.6) for my GeoDjango application. I am following: http://docs.djangoproject.com/en/dev/ref/contrib/gis/install/#creating-a-spatial-database-template-for-postgis I've managed to come up to the point where the provided postgis.sql should be run (i.e. psql -d template_postgis -f $POSTGIS_SQL_PATH/postgis.sql) At that point I am getting an error at the first SQL statement that is tried to be run. When I try that on the psql prompt the result is as follows: template_postgis=# CREATE OR REPLACE FUNCTION st_spheroid_in(cstring) RETURNS spheroid AS '/usr/local/pgsql/lib/postgis-1.5','ellipsoid_in' LANGUAGE 'C' IMMUTABLE STRICT; NOTICE: type "spheroid" is not yet defined DETAIL: Creating a shell type definition. ERROR: could not load library "/usr/local/pgsql/lib/postgis-1.5.so": dlopen(/usr/local/pgsql/lib/postgis-1.5.so, 10): Symbol not found: _DatumGetFloat4 Referenced from: /usr/local/pgsql/lib/postgis-1.5.so Expected in: /opt/local/lib/postgresql83/bin/postgres in /usr/local/pgsql/lib/postgis1.5.so Any ideas what might have been messed up?

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  • Can I ask Postgresql to ignore errors within a transaction

    - by fmark
    I use Postgresql with the PostGIS extensions for ad-hoc spatial analysis. I generally construct and issue SQL queries by hand from within psql. I always wrap an analysis session within a transaction, so if I issue a destructive query I can roll it back. However, when I issue a query that contains an error, it cancels the transaction. Any further queries elicit the following warning: ERROR: current transaction is aborted, commands ignored until end of transaction block Is there a way I can turn this behaviour off? It is tiresome to rollback the transaction and rerun previous queries every time I make a typo.

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  • Grouping rectangles (getting the bounding boxes of rects)

    - by hyn
    What is a good, fast way to get the "final" bounding boxes of a set of random (up to about 40, not many) rectangles? By final I mean that all bounding boxes don't intersect with any other. Brute force way: in a double for loop, for each rect, test for intersection against every other rect. The intersecting rects become a new rect (replaced), indicating the bounding box. Start over and repeat until no intersection is detected. Because the rects are random every time, and the rect count is relatively small, collision detection using spatial hashing seems like overkill. Is there a way to do this more effectively?

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  • GIS: When and why to use ArcObjects over GDAL programming to work with ArcGIS rasters and vectors?

    - by anotherobject
    Im just starting off with GDAL + python to support operations that cannot be done with ArcGIS python geoprocessing scripting. Mainly I am doing spatial modeling/analysis/editing of raster and vector data. I am a bit confused when ArcObject development is required versus when GDAL can be used? Is there functionality of ArcObjects that GDAL does not do? Is the opposite true too? I am assuming that ArcObjects are more useful in developing online tools versus Desktop analysis and modeling where the difference is more to do with preference? In my case i prefer GDAL because of python support, which I believe ArcObjects lack. thanks!

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  • How can I display characters in a map by mapfile?

    - by sirius
    Hello. I'm trying to show a map using postGIS+Mapserver.And I've displayed a PNG picture in my WEB. However, I want to show some charactors in the map, just like this: this is the example from Mapserver Now I'm using database(postgreSQL), but not a shape file. How can I add the charactors then? Here is a part of my mapfile: LAYER CONNECTIONTYPE postgis NAME "state" //Connect to a remote spatial database CONNECTION "user=postgres dbname=*** host=*** password=***" PROCESSING "CLOSE_CONNECTION=DEFER" DATA "the_geom from province" STATUS ON TYPE POLYGON CLASS STYLE COLOR 122 122 122 OUTLINECOLOR 0 0 0 END LABEL COLOR 132 31 31 SHADOWCOLOR 218 218 218 SHADOWSIZE 2 2 TYPE TURETYPE FONT arial-bold SIZE 12 ANTIALIAS TRUE POSITION CL PARTIALS FALSE MINDISTANCE 300 BUFFER 4 END END Some said adding a "TEXT ([*])" in "LABEL", but I don't know howto? Thanks for your help!

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  • GIS: line_locate_point() in Python

    - by miracle2k
    I'm pretty much a beginner when it comes to GIS, but I think I understand the basics - it doesn't seem to hard. But: All these acronyms and different libraries, GEOS, GDAL, PROJ, PCL, Shaply, OpenGEO, OGR, OGC, OWS and what not, each seemingly depending on any number of others, is slightly overwhelming me. Here's what I would like to do: Given a number of points and a linestring, I want to determine the location on the line closest to a certain point. In other words, what PostGIS's line_locate_point() does: http://postgis.refractions.net/documentation/manual-1.3/ch06.html#line%5Flocate%5Fpoint Except I want do use plain Python. Which library or libraries should I have a look at generally for doing these kinds of spatial calculations in Python, and is there one that specifically supports a line_locate_point() equivalent?

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  • How to create a HTML world map with GeoDjango ?

    - by pierre-guillaume-degans
    The GeoDjango tutorial explains how to insert world borders into a spatial database. I would like to create a world Map in HTML with these data, with both map and area tags. Something like that. I just don't know how to retrieve the coordinates for each country (required for the area's coords attribute). from world.models import WorldBorders for country in WorldBorders.objects.all(): print u'<area shape="poly" title="%s" alt="%s" coords="%s" />' % (v.name, v.name, "???") Thanks !

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  • PBE: (Tutorial2) Problem with spatialManager variable

    - by Oleg Tarasenko
    Hi! I've just started with PBE. Now trying to follow few first tutorials. Have problem with the second one(http://pushbuttonengine.com/docs/Lesson-02.html). E.g. this line of code: spatial.spatialManager = PBE.spatialManager; throws the: Attempted access of inaccessible property spatialManager through a reference with static type Class. Could you please help me. these are my first steps with PBE...a bit hard :(

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  • Mysql retrieve polygon data

    - by dskanth
    Hi, i have been developing a site that stores spatial data in mysql database, like that of buildings, gardens, etc. in the form of polygons (latitudes and longitudes). I want to know how to retrieve polygon data in mysql. I have seen this sample query to insert a polygon data: http://amper.110mb.com/SPAT/mysql_initgeometry2.htm But now i want to know how to retrieve data from the table, based on certain constraints like: "where latitude < 9.33 and longitude > 22.4" Also how do i find whether a point lies inside or outside of a polygon

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  • How do I sub sample data by group using ddply?

    - by Maiasaura
    I've got a data frame with far too many rows to be able to do a spatial correlogram. Instead, I want to grab 40 rows for each species and run my correlogram on that subset. I wrote a function to subset a data frame as follows: samp <- function(dataf) { dataf[sample(1:dim(dataf)[1], size=40, replace=FALSE),] } Now I want to apply this function to each species in a larger data frame. When I try something like culled_data = ddply (larger_data, .(species), subset, samp) I get this error: Error in subset.data.frame(piece, ...) : 'subset' must evaluate to logical Anyone got ideas on how to do this?

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  • Best way to search a point across several polygons

    - by user1474341
    I have a requirement whereby I need to match a given point (lat,lon) against several polygons to decide if there is a match. The easiest way would be to iterative over each polygon and apply the point-in-polygon check algorithm, but that is prohibitively expensive. The next optimization that I did was to define a bounding rectangle for each polygon (upper bound, lower bound) and iteratively check the point against the bounding box (fewer comparisons as against checking all the points in the polygon). Is there any other optimization possible? Would a spatial index on the bound rectangle points or a geohash help ? Any guidance would be greatly appreciated. Thanks!

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  • How to optimize method's that track metrics in 3rd party application?

    - by WulfgarPro
    Hi, I have two listboxes that keep updated lists of various objects roaming in a 3rd party application. When a user selects an object from a listbox, an event handler is fired, calling a method that gathers various metrics belonging to that object from the 3rd party application for displaying in a set of textboxes. This is slow! I am not sure how to optimize this functionality to facilitate greater speeds.. private void lsbUavs_SelectedIndexChanged(object sender, EventArgs e) { if (_ourSelectedUavFromListBox != null) { UtilStkScenario.ChangeUavColourOnScenario(_ourSelectedUavFromListBox.UavName, false); } if (lsbUavs.SelectedItem != null) { Uav ourUav = UtilStkScenario.FindUavFromScenarioBasedOnName(lsbUavs.SelectedItem.ToString()); hsbThrottle.Value = (int)ourUav.ThrottleValue; UtilStkScenario.ChangeUavColourOnScenario(ourUav.UavName, true); _ourSelectedUavFromListBox = ourUav; // we don't want this thread spawning many times if (tUpdateMetricInformationInTabControl != null) { if (tUpdateMetricInformationInTabControl.IsAlive) { tUpdateMetricInformationInTabControl.Abort(); } } tUpdateMetricInformationInTabControl = new Thread(UpdateMetricInformationInTabControl); tUpdateMetricInformationInTabControl.Name = "UpdateMetricInformationInTabControlUavs"; tUpdateMetricInformationInTabControl.IsBackground = true; tUpdateMetricInformationInTabControl.Start(lsbUavs); } } delegate string GetNameOfListItem(ListBox listboxId); delegate void SetTextBoxValue(TextBox textBoxId, string valueToSet); private void UpdateMetricInformationInTabControl(object listBoxToUpdate) { ListBox theListBoxToUpdate = (ListBox)listBoxToUpdate; GetNameOfListItem dGetNameOfListItem = new GetNameOfListItem(GetNameOfSelectedListItem); SetTextBoxValue dSetTextBoxValue = new SetTextBoxValue(SetNamedTextBoxValue); try { foreach (KeyValuePair<string, IAgStkObject> entity in UtilStkScenario._totalListOfAllStkObjects) { if (entity.Key.ToString() == (string)theListBoxToUpdate.Invoke(dGetNameOfListItem, theListBoxToUpdate)) { while ((string)theListBoxToUpdate.Invoke(dGetNameOfListItem, theListBoxToUpdate) == entity.Key.ToString()) { if (theListBoxToUpdate.Name == "lsbEntities") { double[] latLonAndAltOfEntity = UtilStkScenario.FindMetricsOfStkObjectOnScenario(UtilStkScenario._stkObjectRoot.CurrentTime, entity.Value); SetEntityOrUavMetricValuesInTextBoxes(dSetTextBoxValue, "Entity", entity.Key, "", "", "", "", latLonAndAltOfEntity[4].ToString(), latLonAndAltOfEntity[3].ToString()); } else if (theListBoxToUpdate.Name == "lsbUavs") { double[] latLonAndAltOfEntity = UtilStkScenario.FindMetricsOfStkObjectOnScenario(UtilStkScenario._stkObjectRoot.CurrentTime, entity.Value); SetEntityOrUavMetricValuesInTextBoxes(dSetTextBoxValue, "UAV", entity.Key, entity.Value.ClassName.ToString(), latLonAndAltOfEntity[0].ToString(), latLonAndAltOfEntity[1].ToString(), latLonAndAltOfEntity[2].ToString(), latLonAndAltOfEntity[4].ToString(), latLonAndAltOfEntity[3].ToString()); } } } } } catch (Exception e) { // selected entity was deleted(end-of-life) in STK - remove LLA information from GUI if (theListBoxToUpdate.Name == "lsbEntities") { SetEntityOrUavMetricValuesInTextBoxes(dSetTextBoxValue, "Entity", "", "", "", "", "", "", ""); UtilLog.Log(e.Message.ToString(), e.GetType().ToString(), "UpdateMetricInformationInTabControl", UtilLog.logWriter); } else if (theListBoxToUpdate.Name == "lsbUavs") { SetEntityOrUavMetricValuesInTextBoxes(dSetTextBoxValue, "UAV", "", "", "", "", "", "", ""); UtilLog.Log(e.Message.ToString(), e.GetType().ToString(), "UpdateMetricInformationInTabControl", UtilLog.logWriter); } } } internal static double[] FindMetricsOfStkObjectOnScenario(object timeToFindMetricState, IAgStkObject stkObject) { double[] stkObjectMetrics = null; try { stkObjectMetrics = new double[5]; object latOfStkObject, lonOfStkObject; double altOfStkObject, headingOfStkObject, velocityOfStkObject; IAgProvideSpatialInfo spatial = stkObject as IAgProvideSpatialInfo; IAgVeSpatialInfo spatialInfo = spatial.GetSpatialInfo(false); IAgSpatialState spatialState = spatialInfo.GetState(timeToFindMetricState); spatialState.FixedPosition.QueryPlanetodetic(out latOfStkObject, out lonOfStkObject, out altOfStkObject); double[] stkObjectheadingAndVelocity = FindHeadingAndVelocityOfStkObjectFromScenario(stkObject.InstanceName); headingOfStkObject = stkObjectheadingAndVelocity[0]; velocityOfStkObject = stkObjectheadingAndVelocity[1]; stkObjectMetrics[0] = (double)latOfStkObject; stkObjectMetrics[1] = (double)lonOfStkObject; stkObjectMetrics[2] = altOfStkObject; stkObjectMetrics[3] = headingOfStkObject; stkObjectMetrics[4] = velocityOfStkObject; } catch (Exception e) { UtilLog.Log(e.Message.ToString(), e.GetType().ToString(), "FindMetricsOfStkObjectOnScenario", UtilLog.logWriter); } return stkObjectMetrics; } private static double[] FindHeadingAndVelocityOfStkObjectFromScenario(string stkObjectName) { double[] stkObjectHeadingAndVelocity = new double[2]; IAgStkObject stkUavObject = null; try { string typeOfObject = CheckIfStkObjectIsEntityOrUav(stkObjectName); if (typeOfObject == "UAV") { stkUavObject = _stkObjectRootToIsolateForUavs.CurrentScenario.Children[stkObjectName]; IAgDataProviderGroup group = (IAgDataProviderGroup)stkUavObject.DataProviders["Heading"]; IAgDataProvider provider = (IAgDataProvider)group.Group["Fixed"]; IAgDrResult result = ((IAgDataPrvTimeVar)provider).ExecSingle(_stkObjectRootToIsolateForUavs.CurrentTime); stkObjectHeadingAndVelocity[0] = (double)result.DataSets[1].GetValues().GetValue(0); stkObjectHeadingAndVelocity[1] = (double)result.DataSets[4].GetValues().GetValue(0); } else if (typeOfObject == "Entity") { IAgStkObject stkEntityObject = _stkObjectRootToIsolateForEntities.CurrentScenario.Children[stkObjectName]; IAgDataProviderGroup group = (IAgDataProviderGroup)stkEntityObject.DataProviders["Heading"]; IAgDataProvider provider = (IAgDataProvider)group.Group["Fixed"]; IAgDrResult result = ((IAgDataPrvTimeVar)provider).ExecSingle(_stkObjectRootToIsolateForEntities.CurrentTime); stkObjectHeadingAndVelocity[0] = (double)result.DataSets[1].GetValues().GetValue(0); stkObjectHeadingAndVelocity[1] = (double)result.DataSets[4].GetValues().GetValue(0); } } catch (Exception e) { UtilLog.Log(e.Message.ToString(), e.GetType().ToString(), "FindHeadingAndVelocityOfStkObjectFromScenario", UtilLog.logWriter); } return stkObjectHeadingAndVelocity; } Any help would be really appreciated. From my knowledge, I cant really see any issues with the C#. Maybe it has to do with the methodology I'm using.. maybe some kind of caching mechanism is required - this is not natively available. WulfgarPro

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  • SQLAuthority News – SQL Server 2012 Upgrade Technical Guide – A Comprehensive Whitepaper – (454 pages – 9 MB)

    - by pinaldave
    Microsoft has just released SQL Server 2012 Upgrade Technical Guide. This guide is very comprehensive and covers the subject of upgrade in-depth. This is indeed a helpful detailed white paper. Even writing a summary of this white paper would take over 100 pages. This further proves that SQL Server 2012 is quite an important release from Microsoft. This white paper discusses how to upgrade from SQL Server 2008/R2 to SQL Server 2012. I love how it starts with the most interesting and basic discussion of upgrade strategies: 1) In-place upgrades, 2) Side by side upgrade, 3) One-server, and 4) Two-server. This whitepaper is not just pure theory but is also an excellent source for some tips and tricks. Here is an example of a good tip from the paper: “If you want to upgrade just one database from a legacy instance of SQL Server and not upgrade the other databases on the server, use the side-by-side upgrade method instead of the in-place method.” There are so many trivia, tips and tricks that make creating the list seems humanly impossible given a short period of time. My friend Vinod Kumar, an SQL Server expert, wrote a very interesting article on SQL Server 2012 Upgrade before. In that article, Vinod addressed the most interesting and practical questions related to upgrades. He started with the fundamentals of how to start backup before upgrade and ended with fail-safe strategies after the upgrade is over. He covered end-to-end concepts in his blog posts in simple words in extremely precise statements. A successful upgrade uses a cycle of: planning, document process, testing, refine process, testing, planning upgrade window, execution, verifying of upgrade and opening for business. If you are at Vinod’s blog post, I suggest you go all the way down and collect the gold mine of most important links. I have bookmarked the blog by blogging about it and I suggest that you bookmark it as well with the way you prefer. Vinod Kumar’s blog post on SQL Server 2012 Upgrade Technical Guide SQL Server 2012 Upgrade Technical Guide is a detailed resource that’s also available online for free. Each chapter was carefully crafted and explained in detail. Here is a quick list of the chapters included in the whitepaper. Before downloading the guide, beware of its size of 9 MB and 454 pages. Here’s the list of chapters: Chapter 1: Upgrade Planning and Deployment Chapter 2: Management Tools Chapter 3: Relational Databases Chapter 4: High Availability Chapter 5: Database Security Chapter 6: Full-Text Search Chapter 7: Service Broker Chapter 8: SQL Server Express Chapter 9: SQL Server Data Tools Chapter 10: Transact-SQL Queries Chapter 11: Spatial Data Chapter 12: XML and XQuery Chapter 13: CLR Chapter 14: SQL Server Management Objects Chapter 15: Business Intelligence Tools Chapter 16: Analysis Services Chapter 17: Integration Services Chapter 18: Reporting Services Chapter 19: Data Mining Chapter 20: Other Microsoft Applications and Platforms Appendix 1: Version and Edition Upgrade Paths Appendix 2: SQL Server 2012: Upgrade Planning Checklist Download SQL Server 2012 Upgrade Technical Guide [454 pages and 9 MB] Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, DBA, PostADay, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, SQL White Papers, SQLAuthority News, SQLServer, T SQL, Technology

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  • Space partitioning when everything is moving

    - by Roy T.
    Background Together with a friend I'm working on a 2D game that is set in space. To make it as immersive and interactive as possible we want there to be thousands of objects freely floating around, some clustered together, others adrift in empty space. Challenge To unburden the rendering and physics engine we need to implement some sort of spatial partitioning. There are two challenges we have to overcome. The first challenge is that everything is moving so reconstructing/updating the data structure has to be extremely cheap since it will have to be done every frame. The second challenge is the distribution of objects, as said before there might be clusters of objects together and vast bits of empty space and to make it even worse there is no boundary to space. Existing technologies I've looked at existing techniques like BSP-Trees, QuadTrees, kd-Trees and even R-Trees but as far as I can tell these data structures aren't a perfect fit since updating a lot of objects that have moved to other cells is relatively expensive. What I've tried I made the decision that I need a data structure that is more geared toward rapid insertion/update than on giving back the least amount of possible hits given a query. For that purpose I made the cells implicit so each object, given it's position, can calculate in which cell(s) it should be. Then I use a HashMap that maps cell-coordinates to an ArrayList (the contents of the cell). This works fairly well since there is no memory lost on 'empty' cells and its easy to calculate which cells to inspect. However creating all those ArrayLists (worst case N) is expensive and so is growing the HashMap a lot of times (although that is slightly mitigated by giving it a large initial capacity). Problem OK so this works but still isn't very fast. Now I can try to micro-optimize the JAVA code. However I'm not expecting too much of that since the profiler tells me that most time is spent in creating all those objects that I use to store the cells. I'm hoping that there are some other tricks/algorithms out there that make this a lot faster so here is what my ideal data structure looks like: The number one priority is fast updating/reconstructing of the entire data structure Its less important to finely divide the objects into equally sized bins, we can draw a few extra objects and do a few extra collision checks if that means that updating is a little bit faster Memory is not really important (PC game)

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  • Hostapd - WLAN as AP

    - by BBK
    I'm trying to start hostapd but without success. I'm using Headless Ubuntu 11.10 oneiric 3.0.0-16-server x86_64. WLAN driver is rt2800usb and my wireless nic card TP-Link TL-WN727N supports AP mode as shows below: us0# ifconfig wlan0 wlan0 Link encap:Ethernet HWaddr 00:27:19:be:cd:b6 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) us0# lsusb Bus 003 Device 003: ID 148f:3070 Ralink Technology, Corp. RT2870/RT3070 Wireless Adapter us0# lshw -C network *-network:3 description: Wireless interface physical id: 4 bus info: usb@3:2 logical name: wlan0 serial: 00:27:19:be:cd:b6 capabilities: ethernet physical wireless configuration: broadcast=yes driver=rt2800usb driverversion=3.0.0-16-server firmware=0.29 link=no multicast=yes wireless=IEEE 802.11bgn us0# hostapd /etc/hostapd/hostapd.conf Configuration file: /etc/hostapd/hostapd.conf Could not read interface wlan0 # The int flags: No such device nl80211 driver initialization failed. ELOOP: remaining socket: sock=4 eloop_data=0xd3e4a0 user_data=0xd3ecc0 handler=0x433880 ELOOP: remaining socket: sock=6 eloop_data=0xd411f0 user_data=(nil) handler=0x43cc10 us0# cat /etc/hostapd/hostapd.conf ssid=Home interface=wlan0 # The interface name of the card #driver=rt2800usb driver=nl80211 macaddr_acl=0 ieee80211n=1 channel=1 hw_mode=g auth_algs=1 ignore_broadcast_ssid=0 wpa=2 wpa_passphrase=88888888 wpa_key_mgmt=WPA-PSK wpa_pairwise=TKIP rsn_pairwise=CCMP us0# iw list Wiphy phy0 Band 1: Capabilities: 0x172 HT20/HT40 Static SM Power Save RX Greenfield RX HT20 SGI RX HT40 SGI RX STBC 1-stream Max AMSDU length: 7935 bytes No DSSS/CCK HT40 Maximum RX AMPDU length 65535 bytes (exponent: 0x003) Minimum RX AMPDU time spacing: 2 usec (0x04) HT RX MCS rate indexes supported: 0-7, 32 TX unequal modulation not supported HT TX Max spatial streams: 1 HT TX MCS rate indexes supported may differ Frequencies: * 2412 MHz [1] (20.0 dBm) * 2417 MHz [2] (20.0 dBm) * 2422 MHz [3] (20.0 dBm) * 2427 MHz [4] (20.0 dBm) * 2432 MHz [5] (20.0 dBm) * 2437 MHz [6] (20.0 dBm) * 2442 MHz [7] (20.0 dBm) * 2447 MHz [8] (20.0 dBm) * 2452 MHz [9] (20.0 dBm) * 2457 MHz [10] (20.0 dBm) * 2462 MHz [11] (20.0 dBm) * 2467 MHz [12] (20.0 dBm) (passive scanning, no IBSS) * 2472 MHz [13] (20.0 dBm) (passive scanning, no IBSS) * 2484 MHz [14] (20.0 dBm) (passive scanning, no IBSS) Bitrates (non-HT): * 1.0 Mbps * 2.0 Mbps (short preamble supported) * 5.5 Mbps (short preamble supported) * 11.0 Mbps (short preamble supported) * 6.0 Mbps * 9.0 Mbps * 12.0 Mbps * 18.0 Mbps * 24.0 Mbps * 36.0 Mbps * 48.0 Mbps * 54.0 Mbps max # scan SSIDs: 4 Supported interface modes: * IBSS * managed * AP * AP/VLAN * WDS * monitor * mesh point Supported commands: * new_interface * set_interface * new_key * new_beacon * new_station * new_mpath * set_mesh_params * set_bss * authenticate * associate * deauthenticate * disassociate * join_ibss * Unknown command (68) * Unknown command (55) * Unknown command (57) * Unknown command (59) * Unknown command (67) * set_wiphy_netns * Unknown command (65) * Unknown command (66) * connect * disconnect The question is: Why the hostapd not starting?

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  • Hadoop, NOSQL, and the Relational Model

    - by Phil Factor
    (Guest Editorial for the IT Pro/SysAdmin Newsletter)Whereas Relational Databases fit the world of commerce like a glove, it is useless to pretend that they are a perfect fit for all human endeavours. Although, with SQL Server, we’ve made great strides with indexing text, in processing spatial data and processing markup, there is still a problem in dealing efficiently with large volumes of ephemeral semi-structured data. Key-value stores such as Cassandra, Project Voldemort, and Riak are of great value for ephemeral data, and seem of equal value as a data-feed that provides aggregations to an RDBMS. However, the Document databases such as MongoDB and CouchDB are ideal for semi-structured data for which no fixed schema exists; analytics and logging are obvious examples. NoSQL products, such as MongoDB, tackle the semi-structured data problem with panache. MongoDB is designed with a simple document-oriented data model that scales horizontally across multiple servers. It doesn’t impose a schema, and relies on the application to enforce the data structure. This is another take on the old ‘EAV’ problem (where you don’t know in advance all the attributes of a particular entity) It uses a clever replica set design that allows automatic failover, and uses journaling for data durability. It allows indexing and ad-hoc querying. However, for SQL Server users, the obvious choice for handling semi-structured data is Apache Hadoop. There will soon be an ODBC Driver for Apache Hive .and an Add-in for Excel. Additionally, there are now two Hadoop-based connectors for SQL Server; the Apache Hadoop connector for SQL Server 2008 R2, and the SQL Server Parallel Data Warehouse (PDW) connector. We can connect to Hadoop process the semi-structured data and then store it in SQL Server. For one steeped in the culture of Relational SQL Databases, I might be expected to throw up my hands in the air in a gesture of contempt for a technology that was, judging by the overblown journalism on the subject, about to make my own profession as archaic as the Saggar makers bottom knocker (a potter’s assistant who helped the saggar maker to make the bottom of the saggar by placing clay in a metal hoop and bashing it). However, on the contrary, I find that I'm delighted with the advances made by the NoSQL databases in the past few years. Having the flow of ideas from the NoSQL providers will knock any trace of complacency out of the providers of Relational Databases and inspire them into back-fitting some features, such as horizontal scaling, with sharding and automatic failover into SQL-based RDBMSs. It will do the breed a power of good to benefit from all this lateral thinking.

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