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I have to recognise text in a picture like this:
Image to recognise
I have tried Tesseract, but I am not very happy with the results.
Could you recommend me any software that could be more accurate in "text recognition on image" instead of "text recognition on document"?
Thanks in advance
Don't expect the Tesseract to work out of the box. This image needs some work before it is put to Tesseract.
I would do following preprocessing:
blur the image to remove some of the digital noise
adaptive thresholding with suitable parameters
correct image
colors to provide white background and black text
this should be easy operations just invert the colors if necessary
run Tesseract with correct language files (italian, I guess?)
These preprocessing steps are really easy to program by hand, but of course there is plenty of libs with this capabilities.
As a starting point see this: Preprocessing image for Tesseract OCR with OpenCV
I don't know of any ready made software that would do text extraction on your specific image without a lot of additional configurations, but you can probably improve your Tesseract results
You can try to treat the image so it's easier for Tesseract to recognize it, use tessedit_write_images true to see your image after Tesseract does it's automatic adjustments
It probably isn't the best so you can do the adjustments yourself with the many libraries/programs available, your goal should be to transform it to a black on white text image, with as little noise as possible
For this read: ImproveQuality
You can also try to train Tesseract for your specific data, but this will require a lot more work, and large amounts of training data, read: TrainingTesseract 4.0
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I have a collection of camera images taken by 4 calibrated cameras mounted on a mobile robot moving in a static outdoor environment. In addition, I have information from a farely accurate OxTS RT3000 Inertial Navigation System (IMU + GPS).
I would like to combine these images to form a 3d model (point cloud) of the static environment. I know there are many Structure from Motion applications, but I would like to find some software/library that is able to make use of the odometry and calibration, at least as an initialization, and to produce a dense point cloud. (All of this is for offline recordings.)
Any suggestions?
Agisoft Photoscan does what you want. From their manual:
PhotoScan supports import of external and internal camera orientation parameters. Thus, if precise camera
data is available for the project, it is possible to load them into PhotoScan along with the photos, to be
used as initial information for 3D reconstruction job.
Taken from page 21 of http://www.agisoft.com/pdf/photoscan-pro_1_4_en.pdf
You may have to do some wrangling of data to get it into a supported format, but it's certainly possible. You'll probably want to use the local coordinate output of the OxTS IMU to go from lat/lon/alt to XYZ and save yourself the conversion. Be careful also to correct for the extrinsic parameters - the rotations and translations between the IMU navigation frame and the cameras.
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I'm trying to develop my own mini animation program like maya, blender, cinema 4d where I can create objects, move them around, render them, etc. Does anyone know any good resources for that? I've found a few but usually when I google for something similar to this all that comes up are game engines. I'm not trying to create a game. And please, don't tell me things like "you need a team", "just use what is already out there", "you're probably not experienced enough"..
Here are some resources I've already found:
https://www.reddit.com/r/cpp/comments/3g1pvf/i_want_to_create_a_3d_engine_from_scratch_where/
https://gamedevelopment.tutsplus.com/tutorials/lets-build-a-3d-graphics-engine-points-vectors-and-basic-concepts--gamedev-8143
https://www.codeproject.com/Articles/1168552/Build-My-Own-D-graphics-engine-step-by-step
Target: Windows
Math
You should know enough linear algebra to know how the various linear transformations in 3D graphics work - translation, scaling, change of coordinate basis, view transformation etc.
You should also know how to render curves and surfaces using splines, Bezier curves, Bezier patches, subdivision methods (e.g., Catmull-Clark) etc.
Mathematics for 3D Game Programming and Computer Graphics is a good place to start if you are unfamiliar with the math.
GUI
After that, you need to pick the libraries for building the application. For building the GUI, if you want to make it easy to port it across platforms, go with Qt. If you only want to target Windows, then go with the native .NET library.
3D Engine
For representing, manipulating, and rendering 3D objects, you could go with the Unity engine. There are a lot of tutorials and books around to teach you how it works.
If you want to go deeper and build your own engine, you can either work with DirectX or OpenGL/Khronos.
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I'm writing a simple software to capture and record webcam images to a compressed video file. I'm using OpenCV "VideoCapture read(frame)" and "VideoWriter write(frame)" in a C++ software.
I'm on Ubuntu 14.04 LTS operating system.
I would like to know which library OpenCV is using under the hood.
Is it ffmpeg or gstreamer or V4L2 or its own low level source code ?
It seems to be changing depending of the OpenCV version I'm using. (Ex 2.4.1, 2.4.11, 3.x)
Can somebody give me a overview of what OpenCV is doing to decode/encode video ?
What is the typical path of the video data coming from the webcam up to my program in user space ?
What is the typical path of the video data coming from program up to the file system ?
Right now, this is confusing for me.
OpenCV uses ffmpeg
I don't know exactly where or how. I know it is used for reading and writing video files. I think it isn't used when getting images from a cam. I think it reads raw cam data, because it can set webcam properties.
Also, the "video" from the web cam isn't video, it is an image at the time the frame is capture. Capturing multiple images in order can be written to a video.
Getting video from a file, OpenCV grabes a frame at a time out of the stream.
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I am looking for sample GLSL fragment shader code that can convert RGB frame (say pixel format as ARGB) to YUV (say YUV420).
Imagine an RGB frame of size 1920x1080. I like to use fragment shader to convert it to YUV frame.
Can you point me to code that can be compiled and run on UBuntu box?
For future reference, a bunch of colorspace conversions in GLSL shaders can be found in Gstreamer gst-plugins-gl codebase :)
First, you should know that your question is poorly phrased. Nobody is going to write you sample code. You can use a search engine (or even search this site) for code to convert from RGB to YUV.
I have written an answer similar to what you're looking for here. It converts from RGB to YIQ, does some shifting of the hue and converts back. You can use the Y'CbCr matrix for the color conversion instead of YIQ, if that's what you need.
It doesn't down-convert to 4:2:0, though. That should be easy enough to do, though. Once it's in Y'CbCr format, you can downsample the appropriate channels as you see fit. I recommend doing a low-pass filter on those channel first to avoid aliasing artifacts.
I don't work with Linux, so haven't tested on Ubuntu. Good luck.
This link has a YUV 4:2:2 v210 to RGB implementation using a compute shader GLSL. YUV 4:2:2 v210 --> RGB GLSL source code
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Is there any tool available which can be use to draw 3D floor plan /Map which gives the code o/p in open GL??
What I want to do is to draw a 3D map of my floor.
It shouldn't be to hard to draw your floor plan in a basic 3D modelling package like Wings3D, export to a basic format like .obj that could be easily parsed.
If you need a 3D package with more options(for texturing,baking lights, etc.) give Blender a try. There are plenty of export options, including .raw (Raw faces) which
an even more basic way to store vertices/faces than .obj. Also it's fairly easy to write
a custom exporter using Blender's Python API which gives you the OpenGL code the way you need it for your setup.