This may not be a programming related but possibly programmers would be in the best position to answer it.
For camera calibration I have a 8 x 8 square pattern printed on sheet of paper. I have to manually enter these co-ordinates into a text file. The software would then pick it up from there and compute the calibration parameters.
Is there a script or some software that I can run on these images and get the pixel co-ordinates of the 4 corners of each of the 64 squares?
You can do this with a traditional chessboard pattern (i.e. black and white squares with no gaps) using cvFindChessboardCorners(). You can read more about the function in the OpenCV API Reference and see some sample code in O'Reilly's OpenCV Book or elsewhere online. As an added bonus, OpenCV has built-in functions that calculate the intrinsic parameters of the camera and an array of extrinsic parameters for the multiple views of a planar calibration object.
I would:
apply threshold and get binarized image.
apply SobelX filter to image. You get an image with the vertical lines. This belong to the sides of the squares that are almost vertical. Keep this as image1.
apply SobelY filter to image. You get an image with the horizontal lines. This belong to the sides of the squares that are almost horizontal. Keep this as image2.
make (image1 xor image2). You get a black image with white pixels indicating the corner positions.
Hope it helps.
I'm sure there are many computer vision libraries with varying capabilities and licenses out there, but one that I can remember off the top of my head is ARToolKit, which should be able to recognize this pattern. And if that's not possible, it comes with a set of very good patterns that are tailored so that they can be recognized even if they're partially obscured.
I don't know ARToolKit (although i've heard a lot about it) but with OpenCV this processing is trivial.
Related
I would like to digitize a book in a similar way to the reCaptcha project. Is there already a system for inputing an image and then outputting little images cropped around words? Any ideas on how to do this?
You should look into the Tesseract OCR project on which reCaptcha was probably based. It has the capability to output the coordinates of recognized words. Then you crop the page to those coords and you are done.
If you just want to split the image in multiple images one word each you could try to find the word bounding boxes and then take those co-ordinates for the splitting. This can be done by taking histograms/projections of the document in horizontal direction and then for each line in vertical direction. An example algorithm with some pictures describing the idea can be found in this paper: "Document Page Decomposition by the Bounding-Box Projection Technique" (http://haralick.org/conferences/71281119.pdf). You could implement this in OpenCV.
Alternativly, you can use Tessaract as mentioned by beppe9000. Perhaps this helps: Getting the bounding box of the recognized words using python-tesseract
But then you get the whole complexity of training OCR even though you only want the bounding boxes.
I'm working on OCR project but I don't know how to remove graphics from the scanned document image before passing it to tesserract.
Some scanned documents which I want to remove graphics are below:
http://www.mediafire.com/view/hvmpty2z3cw3vao/IMG_0087.JPG
http://www.mediafire.com/view/1sgy5s2aaj2o8y3/IMG_0086.JPG
Any advice is very appreciate. Many thanks.
As the text area is usually sparse and does not connect each other, you may consider to have a sobel edge detection on the original image and detect the biggest connection area with some threshold to detect the image area.
Meanwhile, as the image is a rectangle area, another way is to have a Hough translation to detect straight line to consist a rectangle with 4 lines. If you go this way, it’s recommended that you zoom the image first to reduce the calculate complexity.
You can start by detecting text areas using an algorithm available in AForge.Net. See HorizontalRunLengthSmoothing and VerticalRunLengthSmoothing. The algorithm is not very complicated and you can implement easily it using your favorite image processing library. The only constraint is to know approximately the size of the characters in your images.
I'm developing a visualization for certain parts of a Warehouse with Flex 3. In this visualization there are lot of blocks where 1 to x pallets can be placed where x is between 9 and 15. I need to represent each pallet with a black square, each place which is already assigned to a pallet but not physically taken with a grey square and each free place with a white square. I first thought to just use a canvas for each place on a block and change their color if the state changes. But the hundreds of canvases which are there as a result of this approach are not updated quickly enough for my purposes (screen freezes for a few seconds).
I don't want to use embedded images because of the great amount of images I had to embed in the application (those Images appear in 4 orientations).
My idea was to create background images which reflect the state of the whole block only when needed for that certain state and cache them, so that the computation time is spread over the whole runtime.
My problem now is I don't know how to create them in a way that I can use them as "backgroundImages". As far as I understand I would need them as a class object but I don't know how to achieve that, when not embedding the images.
I'm of course open to better approaches to solve my problem. Thanks for your support.
I would suggest using Graphics property of a Sprite for example. It provides basic drawing API, like drawing lines, circles and rectangles.
Besides, you can draw bitmap images on the Graphics to produce more advances results.
My first KML project was an animated map of the Washington DC Metro system (see Animating Metro with KML and Google Earth). Unfortunately, where Metro lines share the same track, only one color prevails. The real map shows a wider line with both colors side by side.
Is there a way to draw a line in KML (Google Earth) with two side-by-side colors? I've seen a way to have a different color on the edges of the line, but that's different.
I could cheat by changing the coordinates of each station, but aside from computational difficulties, I'd have to continuously changes to positions every time the user zooms, to prevent a gap between colors (or an overlap).
Other subway systems show more than two colors running alongside each other, so an option to show multiple colors would be nice. And this is not really a gradient, as the colors don't fade together; they should be distinct, assuming the pixel width is wide enough.
This is probably a feature request, though surely someone else has run across this problem before Google Earth v6? Would love to be able to do this, or find a good workaround in the interim.
Michael
http://www.mvjantzen.com/blog/
The short answer is no, although you could probably create a custom MVC object that renders the line for you as desired (i.e. you would not need to alter the Kml)
http://code.google.com/apis/maps/articles/mvcfun.html
That said, your cheat method could work too - and I would disagree that
"...I'd have to continuously changes to positions every time the user
zooms, to prevent a gap between colors"
You can set the <gx:physicalWidth> property which allows you to set the width of a LineString to be in meters, rather than pixels.
https://developers.google.com/kml/documentation/kmlreference#gxphysicalwidth
In the case of your track example, this means you can set the width of the track to match the underlying imagery no matter what altitude the end user views it from.
I have an image of a basic game map. Think of it as just horizontal and vertical walls which can't be crossed. How can I go from a png image of the walls to something in code easily?
The hard way is pretty straight forward... it's just if I change the image map I would like an easy way to translate that to code.
Thanks!
edit: The map is not tile-based. It's top down 2D.
I dabble in video games, and I personally would not want the hassle of checking the boundaries of pictures on the map. Wouldn't it be cleaner if these walls were objects that just happened to have an image property (or something like it)? The image would display, but the object would have well defined coordinates and a function could decide whether an object was hit every time the player moved.
I need more details.
Is your game tile based? Is it 3d?
If its tile based, you could downsample your image to the tile resolution and then do a 1:1 conversion with each pixel representing a tile.
I suggest writing a script that takes each individual pixel and determines if it represents part of a wall or not (ie black or white). Then, code your game so that walls are built from individual little block, represented by the pixels. Shouldn't be TOO hard...
If you don't need to precompute anything using the map info. You can just check in runtime logic using getPixel(x,y) like function.
Well, i can see two cases with two different "best solution" depending on where your graphic comes from:
Your graphics is tiled, and thus you can easily "recognize" a block because it's using the same graphics as other blocks and all you would have to do is a program that, when given a list of "blocking tiles" and a map can produce a "collision map" by comparing each tile with tiles in the "blocking list".
Your graphics is just some graphics (e.g. it could be a picture, or some CG graphics) and you don't expect pixels for a block to be the same as pixels from another block. You could still try to apply an "edge detection" algorithm on your picture, but my guess is then that you should rather split your picture in a BG layer and a FG layer so that the FG layer has a pre-defined color (or alpha=0) and test pixels against that color to define whether things are blocking or not.
You don't have much blocking shapes, but they are usually complex (polygons, ellipses) and would be unefficient to render using a bitmap of the world or to pack as "tile attributes". This is typically the case for point-and-click adventure games, for instance. In that case, you're probably to create path that match your boundaries with a vector drawing program and dig for a library that does polygon intersection or bezier collisions.
Good luck and have fun.