Search Results

Search found 442 results on 18 pages for 'the naive'.

Page 13/18 | < Previous Page | 9 10 11 12 13 14 15 16 17 18  | Next Page >

• In a digital photo, how can I detect if a mountain is obscured by clouds?

  - by Gavin Brock

  The problem I have a collection of digital photos of a mountain in Japan. However the mountain is often obscured by clouds or fog. What techniques can I use to detect that the mountain is visible in the image? I am currently using Perl with the Imager module, but open to alternatives. All the images are taken from the exact same position - these are some samples. My naïve solution I started by taking several horizontal pixel samples of the mountain cone and comparing the brightness values to other samples from the sky. This worked well for differentiating good image 1 and bad image 2. However in the autumn it snowed and the mountain became brighter than the sky, like image 3, and my simple brightness test started to fail. Image 4 is an example of an edge case. I would classify this as a good image since some of the mountain is clearly visible. UPDATE 1 Thank you for the suggestions - I am happy you all vastly over-estimated my competence. Based on the answers, I have started trying the ImageMagick edge-detect transform, which gives me a much simpler image to analyze. convert sample.jpg -edge 1 edge.jpg I assume I should use some kind of masking to get rid of the trees and most of the clouds. Once I have the masked image, what is the best way to compare the similarity to a 'good' image? I guess the "compare" command suited for this job? How do I get a numeric 'similarity' value from this?

  Read the article

• Efficient cron job utilizing Zend_Mail_Storage_Imap.

  - by fireeyedboy

  I'm new to the IMAP protocol and Zend_Mail_Storage and I'm writing a small php script for a cron job that should regularly poll an IMAP account and check for new messages, and send an e-mail if new messages have arrived. As you can imagine, I want to only poll the IMAP account for relevant messages, and I only want to send a new e-mail if new messages have arrived since the last polled new message. So I thought of keeping track of the last message I polled with some unique identifier for a message. But I'm a bit uncertain about whether the methods I want to utilize for this do what I expect them to do though. So my questions are: Does the iterator position of Zend_Mail_Storage_Imap actually resemble some IMAP unique identifier for messages, or is it simply only and internal position of Zend_Mail_Storage_Abstract? For instance, if I tell it to seek() to message 5 (which I stored from an earlier session) will it indeed seek to the appropriate message on the IMAP server, even if for instance messages have been deleted since last session? Would keeping track of this latest polled message id in a file suffice for a cron job that, say, polls the account every 5 or 10 minutes? Or is this too naive, and should I be using a database for instance. Or is there maybe a much easier way to keep track of such state with Zend_Mail_Storage_Abstract? Also, do I need to poll every IMAP folder? Or is everything accumulated when I poll INBOX? If you could shed some light on any of these matters, I'ld appreciate it. Thanks in advance.

  Read the article

• Count all lists of adjacent nodes stored in an array.

  - by Ben Brodie

  There are many naive approaches to this problem, but I'm looking for a good solution. Here is the problem (will be implemented in Java): You have a function foo(int a, int b) that returns true if 'a' is "adjacent" to 'b' and false if 'a' is not adjacent to 'b'. You have an array such as this [1,4,5,9,3,2,6,15,89,11,24], but in reality has a very long length, like 120, and will be repeated over and over (its a genetic algorithm fitness function) which is why efficiency is important. I want a function that returns the length of each possible 'list' of adjacencies in the array, but not including the 'lists' which simply subsets of a larger list. For example, if foo(1,4) - true, foo(4,5) - true, foo(5,9)- false, foo(9,3) & foo(3,2) & foo(2,6), foo(6,15) - true, then there are 'lists' (1,4,5) and (9,3,2,6), so length 3 and 4. I don't want it to return (3,2,6), though, because this is simply a subset of 9,3,2,6. Thanks.

  Read the article

• Career Plan: The one year plan. The three year plan.

  - by drelihan

  Hi Folks, I work as a developer however I only recently began developing full time having worked for 5 years in various roles. When it comes to career planning I think I pretty much agree with The Journeyman to Craftsman model coined in The Pragmatic Probrammer and used by Bob Martin. I see myself as a journeyman and I won't call myself a "good" (for want of a better word) until I re-evaluate my skills in 5 years time. However, as part of our careers we are encouraged to make one and three year plan with specific goals that we should hit. Unfortunately, my goal is this: Write clean code that solves a problem and is easy to maintain. From a technology point of view I want to know C++ and .net programming inside out(C#, WCF etc..) But that's it. That's my plan. Is this enough? So although there's a great discussion on what people should do with their career: http://stackoverflow.com/questions/11313/career-planning-any-tips My question is this: What's your one year plan? What's your three year plan? And am I being naive with my career? Thanks,

  Read the article

• Design pattern to keep track UITableView rows correspondance to underlying data in constant time.

  - by DenNukem

  When my model changes I want to animate changes in UITableView by inserting/deleting rows. For that I need to know the ordinal of the given row (so I can construct NSIndexPath), which I find hard to do in better-than-linear time. For example, consider that I have a list of addressbook entries which are manualy sorted by the user, i.e. there is no ordering "key" that represents the sort order. There is also a corresponding UITableView that shows one row per addressbook entry. When UITableView queries the datasource I query the NSMUtableArray populated with my entries and return required data in constant time for each row. However, if there is a change in underlying model I am getting a notification "Joe Smith, id#123 has been removed". Now I have a dilemma. A naive approach would be to scan the array, determine the index at which Joe Smith is and then ask UITableView to remove that precise row from the view, also removing it form the array. However, the scan will take linear time to finish. Now I could have an NSDictionary which allows me to find Joe Smith in constant time, but that doesn't do me a lot of good because I still need to find his ordinal index within the array in order to instruct UITableView to remove that row, which is again a linear search. I could further decide to store each object's ordinal inside the object itself to make it constant, but it will become outdated after first such update as all subsequent index values will have changed due to removal of an object. So what is the correct design pattern to accurately reflect model changes in the UITableView in costant (or at least logarithmic) time?

  Read the article

• Triangle numbers problem....show within 4 seconds

  - by Daredevil

  The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28. The first ten terms would be: 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ... Let us list the factors of the first seven triangle numbers: 1: 1 3: 1,3 6: 1,2,3,6 10: 1,2,5,10 15: 1,3,5,15 21: 1,3,7,21 28: 1,2,4,7,14,28 We can see that 28 is the first triangle number to have over five divisors. Given an integer n, display the first triangle number having at least n divisors. Sample Input: 5 Output 28 Input Constraints: 1<=n<=320 I was obviously able to do this question, but I used a naive algorithm: Get n. Find triangle numbers and check their number of factors using the mod operator. But the challenge was to show the output within 4 seconds of input. On high inputs like 190 and above it took almost 15-16 seconds. Then I tried to put the triangle numbers and their number of factors in a 2d array first and then get the input from the user and search the array. But somehow I couldn't do it: I got a lot of processor faults. Please try doing it with this method and paste the code. Or if there are any better ways, please tell me.

  Read the article

• Turing Machine & Modern Computer

  - by smwikipedia

  I heard a lot that modern computers are based on Turing machine. I'd like to share my understanding and hear your comments. I think the computer is a big general-purpose Turing machine. Each program we write is a small specific-purpose Turing machine. The classical Turing machine do its job based on the input and its current state inside and so do our programs. Let's take a running program (a process) as an example. We know that in the process's address space, there's areas for stack, heap, and code. A classical Turing machine doesn't have the ability to remember many things, so we borrow the concept of stack from the push-down automaton. The heap and stack areas contains the state of our specific-purpose Turing machine (our program). The code area represents the logic of this small Turing machine. And various I/O devices supply input to this Turing machine. The above is my naive understanding about the working paradigm of modern computer. I couln't wait to hear your comments. Thanks very much.

  Read the article

• MySQL-python 1.2.3 and OS X 10.5: 64- or 32-bit?

  - by Dave Everitt

  I've been happily using Django and MySQL in development on an existing machine running OS X 10.4 Tiger, and have set up a similar environment in 10.5 Leopard on a new 64-bit MacBook, with a working MySQL and Python 2.6.4. However, now I want them to communicate, easy_install MySQL-python gave ld warnings that the file is not of the required architecture, which led me to test my Python 2.4.6 install (from the Mac OS X disc image): >>> import sys >>> sys.maxint 2147483647 Ah. So my Python install appears to be 32-bit and (I think?) won't install MySQL-python for my 64-bit MySQL. There are lots of hacks out there for MySQL-python on OS X (mostly 1.2.2), but - after hours of reading - I'm pretty sure they won't fix this architecture mismatch. So I'm stuck because I can't decide whether to: give up, remove the 64-bit MySQL install (thorough methods, please?) and use the 32-bit MySQL disc image instead; re-install Python in 64-bit mode from the tarball, --with-universal archs-64-bit and --enable-universalsdk= as detailed in Python.org's 2.6 news. So my questions for anyone who has encountered this issue are: Is installing 64-bit Python on OS X 10.5 worth bothering with? If so, (naive, lazy question!) how are the two required arguments combined? If I just skip along in 32-bit (as on my working setup) what am I missing? I'm after a hassle-free install that's easy to reproduce on other machines (possible student use) so I'd really welcome your opinions, please!

  Read the article

• Can Haskell's Parsec library be used to implement a recursive descent parser with backup?

  - by Thor Thurn

  I've been considering using Haskell's Parsec parsing library to parse a subset of Java as a recursive descent parser as an alternative to more traditional parser-generator solutions like Happy. Parsec seems very easy to use, and parse speed is definitely not a factor for me. I'm wondering, though, if it's possible to implement "backup" with Parsec, a technique which finds the correct production to use by trying each one in turn. For a simple example, consider the very start of the JLS Java grammar: Literal: IntegerLiteral FloatingPointLiteral I'd like a way to not have to figure out how I should order these two rules to get the parse to succeed. As it stands, a naive implementation like this: literal = do { x <- try (do { v <- integer; return (IntLiteral v)}) <|> (do { v <- float; return (FPLiteral v)}); return(Literal x) } Will not work... inputs like "15.2" will cause the integer parser to succeed first, and then the whole thing will choke on the "." symbol. In this case, of course, it's obvious that you can solve the problem by re-ordering the two productions. In the general case, though, finding things like this is going to be a nightmare, and it's very likely that I'll miss some cases. Ideally, I'd like a way to have Parsec figure out stuff like this for me. Is this possible, or am I simply trying to do too much with the library? The Parsec documentation claims that it can "parse context-sensitive, infinite look-ahead grammars", so it seems like something like I should be able to do something here.

  Read the article

• How to count term frequency for set of documents?

  - by ManBugra

  i have a Lucene-Index with following documents: doc1 := { caldari, jita, shield, planet } doc2 := { gallente, dodixie, armor, planet } doc3 := { amarr, laser, armor, planet } doc4 := { minmatar, rens, space } doc5 := { jove, space, secret, planet } so these 5 documents use 14 different terms: [ caldari, jita, shield, planet, gallente, dodixie, armor, amarr, laser, minmatar, rens, jove, space, secret ] the frequency of each term: [ 1, 1, 1, 4, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1 ] for easy reading: [ caldari:1, jita:1, shield:1, planet:4, gallente:1, dodixie:1, armor:2, amarr:1, laser:1, minmatar:1, rens:1, jove:1, space:2, secret:1 ] What i do want to know now is, how to obtain the term frequency vector for a set of documents? for example: Set<Documents> docs := [ doc2, doc3 ] termFrequencies = magicFunction(docs); System.out.pring( termFrequencies ); would result in the ouput: [ caldari:0, jita:0, shield:0, planet:2, gallente:1, dodixie:1, armor:2, amarr:1, laser:1, minmatar:0, rens:0, jove:0, space:0, secret:0 ] remove all zeros: [ planet:2, gallente:1, dodixie:1, armor:2, amarr:1, laser:1 ] Notice, that the result vetor contains only the term frequencies of the set of documents. NOT the overall frequencies of the whole index! The term 'planet' is present 4 times in the whole index but the source set of documents only contains it 2 times. A naive implementation would be to just iterate over all documents in the docs set, create a map and count each term. But i need a solution that would also work with a document set size of 100.000 or 500.000. Is there a feature in Lucene i can use to obtain this term vector? If there is no such feature, how would a data structure look like someone can create at index time to obtain such a term vector easily and fast? I'm not that Lucene expert so i'am sorry if the solution is obvious or trivial.

  Read the article

• How can I randomly iterate through a large Range?

  - by void

  I would like to randomly iterate through a range. Each value will be visited only once and all values will eventually be visited. For example: class Array def shuffle ret = dup j = length i = 0 while j > 1 r = i + rand(j) ret[i], ret[r] = ret[r], ret[i] i += 1 j -= 1 end ret end end (0..9).to_a.shuffle.each{|x| f(x)} where f(x) is some function that operates on each value. A Fisher-Yates shuffle is used to efficiently provide random ordering. My problem is that shuffle needs to operate on an array, which is not cool because I am working with astronomically large numbers. Ruby will quickly consume a large amount of RAM trying to create a monstrous array. Imagine replacing (0..9) with (0..99**99). This is also why the following code will not work: tried = {} # store previous attempts bigint = 99**99 bigint.times { x = rand(bigint) redo if tried[x] tried[x] = true f(x) # some function } This code is very naive and quickly runs out of memory as tried obtains more entries. What sort of algorithm can accomplish what I am trying to do? [Edit1]: Why do I want to do this? I'm trying to exhaust the search space of a hash algorithm for a N-length input string looking for partial collisions. Each number I generate is equivalent to a unique input string, entropy and all. Basically, I'm "counting" using a custom alphabet. [Edit2]: This means that f(x) in the above examples is a method that generates a hash and compares it to a constant, target hash for partial collisions. I do not need to store the value of x after I call f(x) so memory should remain constant over time. [Edit3/4/5/6]: Further clarification/fixes.

  Read the article

• Unexpected performance curve from CPython merge sort

  - by vkazanov

  I have implemented a naive merge sorting algorithm in Python. Algorithm and test code is below: import time import random import matplotlib.pyplot as plt import math from collections import deque def sort(unsorted): if len(unsorted) <= 1: return unsorted to_merge = deque(deque([elem]) for elem in unsorted) while len(to_merge) > 1: left = to_merge.popleft() right = to_merge.popleft() to_merge.append(merge(left, right)) return to_merge.pop() def merge(left, right): result = deque() while left or right: if left and right: elem = left.popleft() if left[0] > right[0] else right.popleft() elif not left and right: elem = right.popleft() elif not right and left: elem = left.popleft() result.append(elem) return result LOOP_COUNT = 100 START_N = 1 END_N = 1000 def test(fun, test_data): start = time.clock() for _ in xrange(LOOP_COUNT): fun(test_data) return time.clock() - start def run_test(): timings, elem_nums = [], [] test_data = random.sample(xrange(100000), END_N) for i in xrange(START_N, END_N): loop_test_data = test_data[:i] elapsed = test(sort, loop_test_data) timings.append(elapsed) elem_nums.append(len(loop_test_data)) print "%f s --- %d elems" % (elapsed, len(loop_test_data)) plt.plot(elem_nums, timings) plt.show() run_test() As much as I can see everything is OK and I should get a nice N*logN curve as a result. But the picture differs a bit: Things I've tried to investigate the issue: PyPy. The curve is ok. Disabled the GC using the gc module. Wrong guess. Debug output showed that it doesn't even run until the end of the test. Memory profiling using meliae - nothing special or suspicious. ` I had another implementation (a recursive one using the same merge function), it acts the similar way. The more full test cycles I create - the more "jumps" there are in the curve. So how can this behaviour be explained and - hopefully - fixed? UPD: changed lists to collections.deque UPD2: added the full test code UPD3: I use Python 2.7.1 on a Ubuntu 11.04 OS, using a quad-core 2Hz notebook. I tried to turn of most of all other processes: the number of spikes went down but at least one of them was still there.

  Read the article

• HTTP POST prarameters order / REST urls

  - by pq

  Let's say that I'm uploading a large file via a POST HTTP request. Let's also say that I have another parameter (other than the file) that names the resource which the file is updating. The resource cannot be not part of the URL the way you can do it with REST (e.g. foo.com/bar/123). Let's say this is due to a combination of technical and political reasons. The server needs to ignore the file if the resource name is invalid or, say, the IP address and/or the logged in user are not authorized to update the resource. Looks like, if this POST came from an HTML form that contains the resource name first and file field second, for most (all?) browsers, this order is preserved in the POST request. But it would be naive to fully rely on that, no? In other words the order of HTTP parameters is insignificant and a client is free to construct the POST in any order. Isn't that true? Which means that, at least in theory, the server may end up storing the whole large file before it can deny the request. It seems to me that this is a clear case where RESTful urls have an advantage, since you don't have to look at the POST content to perform certain authorization/error checking on the request. Do you agree? What are your thoughts, experiences?

  Read the article

• Need some ignition for learning Embedded Systems

  - by Rahul

  I'm very much interested in building applications for Embedded Devices. I'm in my 3rd year Electrical Engineering and I'm passionate about coding, algorithms, Linux OS, etc. And also by Googling I found out that Linux OS is one of the best OSes for Embedded devices(may be/may not be). I want to work for companies which work on mobile applications. I'm a newbie/naive to this domain & my skills include C/C++ & MySQL. I need help to get started in the domain of Embedded Systems; like how/where to start off, Hardware prerequisites, necessary programming skills, also what kind of Embedded Applications etc. I've heard of ARM, firmware, PIC Micorcontrollers; but I don't know anything & just need proper introduction about them. Thanx. P.S: I'm currently reading Bjarne Struotsup's lecture in C++ at Texas A&M University, and one chapter in it describes about Embedded Systems Programming.

  Read the article

• how do I paste text to a line by line text filter like awk, without having stdin echo to the screen?

  - by Barton Chittenden

  I have a text in an email on a windows box that looks something like this: 100 some random text 101 some more random text 102 lots of random text, all different 103 lots of random text, all the same I want to extract the numbers, i.e. the first word on each line. I've got a terminal running bash open on my Linux box... If these were in a text file, I would do this: awk '{print $1}' mytextfile.txt I would like to paste these in, and get my numbers out, without creating a temp file. my naive first attempt looked like this: $ awk '{print $1}' 100 some random text 100 101 some more random text 101 102 lots of random text, all different 103 lots of random text, all the same 102 103 The buffering of stdin and stdout make a hash of this. I wouldn't mind if stdin all printed first, followed by all of stdout; this is what would happen if I were to paste into 'sort' for example, but awk and sed are a different story. a little more thought gave me this: open two terminals. Create a fifo file. Read from the fifo on one terminal, write to it on another. This does in fact work, but I'm lazy. I don't want to open a second terminal. Is there a way in the shell that I can hide the text echoed to the screen when I'm passing it in to a pipe, so that I paste this: 100 some random text 101 some more random text 102 lots of random text, all different 103 lots of random text, all the same but see this? $ awk '{print $1}' 100 101 102 103

  Read the article

• Sending series of images to display like a movie on iPhone

  - by unknownthreat

  Allow me to elaborate more. On the server, we will have a program that will take data from iPhone and process that data and produce series of images. Each time an image is generated, it will be send back to display on iPhone. I have done all of the things above using UDP, OpenGL, and such. It works. The images are transferred to iPhone and can be displayed, but it is slow. The image's resolution is around 320 x 420 and we send the image pixels by pixels. This naive implementation leads to a slow framerate. I can see around 2-3 frames per second. There are also some UDP packets dropped, and this is expected. Are there any sort of compression method available for something like this? Are there any other method that can make this better? NOTE: please don't just write "compression" as an answer, because we are aware that we will need to do it in some ways.

  Read the article

• Classification: Dealing with Abstain/Rejected Class

  - by abner.ayala

  I am asking for your input and/help on a classification problem. If anyone have any references that I can read to help me solve my problem even better. I have a classification problem of four discrete and very well separated classes. However my input is continuous and has a high frequency (50Hz), since its a real-time problem. The circles represent the clusters of the classes, the blue line the decision boundary and Class 5 equals the (neutral/resting do nothing class). This class is the rejected class. However the problem is that when I move from one class to the other I activate a lot of false positives in the transition movements, since the movement is clearly non-linear. For example, every time I move from class 5 (neutral class) to 1 I first see a lot of 3's before getting to the 1 class. Ideally, I will want my decision boundary to look like the one in the picture below where the rejected class is Class =5. Has a higher decision boundary than the others classes to avoid misclassification during transition. I am currently implementing my algorithm in Matlab using naive bayes, kNN, and SVMs optimized algorithms using Matlab. Question: What is the best/common way to handle abstain/rejected classes classes? Should I use (fuzzy logic, loss function, should I include resting cluster in the training)?

  Read the article

• How to identify ideas and concepts in a given text

  - by Nick

  I'm working on a project at the moment where it would be really useful to be able to detect when a certain topic/idea is mentioned in a body of text. For instance, if the text contained: Maybe if you tell me a little more about who Mr Balzac is, that would help. It would also be useful if I could have a description of his appearance, or even better a photograph? It'd be great to be able to detect that the person has asked for a photograph of Mr Balzac. I could take a really naïve approach and just look for the word "photo" or "photograph", but this would obviously be no good if they wrote something like: Please, never send me a photo of Mr Balzac. Does anyone know where to start with this? Is it even possible? I've looked into things like nltk, but I've yet to find an example of someone doing something similar and am still not entirely sure what this kind of analysis is called. Any help that can get me off the ground would be great. Thanks!

  Read the article

• How to get user input before saving a file in Sublime Text

  - by EddieJessup

  I'm making a plugin in Sublime Text that prompts the user for a password to encrypt a file before it's saved. There's a hook in the API that's executed before a save is executed, so my naïve implementation is: class TranscryptEventListener(sublime_plugin.EventListener): def on_pre_save(self, view): # If document is set to encode on save if view.settings().get('ON_SAVE'): self.view = view # Prompt user for password message = "Create a Password:" view.window().show_input_panel(message, "", self.on_done, None, None) def on_done(self, password): self.view.run_command("encode", {password": password}) The problem with this is, by the time the input panel appears for the user to enter their password, the document has already been saved (despite the trigger being 'on_pre_save'). Then once the user hits enter, the document is encrypted fine, but the situation is that there's a saved plaintext file, and a modified buffer filled with the encrypted text. So I need to make Sublime Text wait until the user's input the password before carrying out the save. Is there a way to do this? At the moment I'm just manually re-saving once the encryption has been done: def on_pre_save(self, view, encode=False): if view.settings().get('ON_SAVE') and not view.settings().get('ENCODED'): self.view = view message = "Create a Password:" view.window().show_input_panel(message, "", self.on_done, None, None) def on_done(self, password): self.view.run_command("encode", {password": password}) self.view.settings().set('ENCODED', True) self.view.run_command('save') self.view.settings().set('ENCODED', False) but this is messy and if the user cancels the encryption then the plaintext file gets saved, which isn't ideal. Any thoughts? Edit: I think I could do it cleanly by overriding the default save command. I hoped to do this by using the on_text_command or on_window_command triggers, but it seems that the save command doesn't trigger either of these (maybe it's an application command? But there's no on_application_command). Is there just no way to override the save function?

  Read the article

• Reading text files line by line, with exact offset/position reporting

  - by Benjamin Podszun

  Hi. My simple requirement: Reading a huge ( a million) line test file (For this example assume it's a CSV of some sorts) and keeping a reference to the beginning of that line for faster lookup in the future (read a line, starting at X). I tried the naive and easy way first, using a StreamWriter and accessing the underlying BaseStream.Position. Unfortunately that doesn't work as I intended: Given a file containing the following Foo Bar Baz Bla Fasel and this very simple code using (var sr = new StreamReader(@"C:\Temp\LineTest.txt")) { string line; long pos = sr.BaseStream.Position; while ((line = sr.ReadLine()) != null) { Console.Write("{0:d3} ", pos); Console.WriteLine(line); pos = sr.BaseStream.Position; } } the output is: 000 Foo 025 Bar 025 Baz 025 Bla 025 Fasel I can imagine that the stream is trying to be helpful/efficient and probably reads in (big) chunks whenever new data is necessary. For me this is bad.. The question, finally: Any way to get the (byte, char) offset while reading a file line by line without using a basic Stream and messing with \r \n \r\n and string encoding etc. manually? Not a big deal, really, I just don't like to build things that might exist already..

  Read the article

• Automatic tracking algorithm

  - by nico

  Hi everyone, I'm trying to write a simple tracking routine to track some points on a movie. Essentially I have a series of 100-frames-long movies, showing some bright spots on dark background. I have ~100-150 spots per frame, and they move over the course of the movie. I would like to track them, so I'm looking for some efficient (but possibly not overkilling to implement) routine to do that. A few more infos: the spots are a few (es. 5x5) pixels in size the movement are not big. A spot generally does not move more than 5-10 pixels from its original position. The movements are generally smooth. the "shape" of these spots is generally fixed, they don't grow or shrink BUT they become less bright as the movie progresses. the spots don't move in a particular direction. They can move right and then left and then right again the user will select a region around each spot and then this region will be tracked, so I do not need to automatically find the points. As the videos are b/w, I though I should rely on brigthness. For instance I thought I could move around the region and calculate the correlation of the region's area in the previous frame with that in the various positions in the next frame. I understand that this is a quite naïve solution, but do you think it may work? Does anyone know specific algorithms that do this? It doesn't need to be superfast, as long as it is accurate I'm happy. Thank you nico

  Read the article

• Unable to render php files in browser

  - by p1

  Hello, I am very new to php, and I am trying to develop a facebook application using php. I am using Joyent as my hosting platform. Currently, I am trying to do some simple scripts in php and then build on them. However I am unable to see any php files being rendered properly in my application. For eg: I have a simple script called phpinfo.php: If I execute this on terminal like php phpinfo.php , I can see all the configurations. However if I try to access the same file as http://xxxxxx.facebook.joyent.us/phpinfo.php, I get : Internal Server Error The server encountered an internal error or misconfiguration and was unable to complete your request. Even if I rename this file to index.php its still the same. However I am able to access other html files [index.html] on the same location . These are some of my php settings: These are some of the settings: [fbkusoni:~/web/public] aafhe7vh$ php phpinfo.php | grep On allow_url_fopen = On = On auto_globals_jit = On = On enable_dl = On = On file_uploads = On = On ignore_repeated_errors = On = On ignore_repeated_source = On = On implicit_flush = On = On log_errors = On = On register_argc_argv = On = On report_memleaks = On = On y2k_compliance = On = On Multibyte regex (oniguruma) backtrack check = On mysql.allow_persistent = On = On session.bug_compat_warn = On = On session.use_cookies = On = On suhosin.cookie.cryptdocroot = On = On suhosin.cookie.cryptua = On = On suhosin.mt_srand.ignore = On = On suhosin.protectkey = On = On suhosin.server.encode = On = On suhosin.server.strip = On = On suhosin.session.cryptdocroot = On = On suhosin.session.cryptua = On = On suhosin.session.encrypt = On = On suhosin.srand.ignore = On = On suhosin.stealth = On = On The answer might be very naive, but I am just trying to get started and looking for any suggestions regarding this and also using Joyent and cakephp to develop facebook applications. Thanks.

  Read the article

• Scaling Image to multiple sizes for Deep Zoom

  - by AnthonyWJones

  Lets assume I have a bitmap with a square aspect and width of 2048 pixels. In order to create a set of files need by Silverlight's DeepZoomImageTileSource I need to scale this bitmap to 1024 then to 512 then to 256 etc down to 1 pixel image. There are two, I suspect naive, approaches:- For each image required scale the original full size image to the required size. However it seems excessive to be scaling the full image to the very small sizes. Having scaled from one level to the next discard the original image and scale each sucessive scaled image as the source of the next smaller image. However I suspect that this would generate images in the 256-64 range with poor fidelity than using option 1. Note unlike with the Deep Zoom Composer this tool is expected to act in an on-demand fashion hence it needs to complete in a reasonable timeframe (tops 30 seconds). On the pluse side I'm only creating a single multiscale image not a pyramid of mutliple high-res images. I am outside my comfort zone here, any graphics experts got any advice? Am I wrong about point 2? Is point 1 reasonably performant and I'm worrying about nothing? Option 3?

  Read the article

• bash: listing files in date order, with spaces in filenames

  - by Jason Judge

  I am starting with a file containing a list of hundreds of files (full paths) in a random order. I would like to list the details of the ten latest files in that list. This is my naive attempt: ls -las -t `cat list-of-files.txt` | head -10 That works, so long as none of the files have spaces in, but fails if they do as those files are split up at the spaces and treated as separate files. I have tried quoting the files in the original list-of-files file, but the here-document still splits the files up at the spaces in the filenames. The only way I can think of doing this, is to ls each file individually (using xargs perhaps) and create an intermediate file with the file listings and the date in a sortable order as the first field in each line, then sort that intermediate file. However, that feels a bit cumbersome and inefficient (hundreds of ls commands rather than one or two). But that may be the only way to do it? Is there any way to pass "ls" a list of files to process, where those files could contain spaces - it seems like it should be simple, but I'm stumped.

  Read the article

• QuadTrees - how to update when internal items are moving

  - by egarcia

  I've implemented a working QuadTree. It subdivides 2-d space in order to accomodate items, identified by their bounding box (x,y,width,height) on the smallest possible quad (up to a minimum area). My code is based on this implementation (mine is in Lua instead of C#) : http://www.codeproject.com/KB/recipes/QuadTree.aspx I've been able to successfully implement insertions and deletions successfully. I've turn now my attention to the update() function, since my items' position and dimensions change over time. My first implementation works, but it is quite naïve: function QuadTree:update(item) self:remove(item) return self.root:insert(item) end Yup, I basically remove and reinsert every item every time they move. This works, but I'd like to optimize it a bit more; after all, most of the time, moving items still remain on the same quadTree node most of the iterations. Is there any standard way to deal with this kind of update? In case it helps, my code is here: http://github.com/kikito/passion/blob/master/ai/QuadTree.lua I'm not looking for someone to implement it for me; pointers to an existing working implementation (even in other languages) would suffice.

  Read the article

< Previous Page | 9 10 11 12 13 14 15 16 17 18  | Next Page >