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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 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'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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In the "slam for dummies" tutorial, laser scanner was used, and two methods of landmark extraction were shown.
But most practical SLAM implementations are based on camera images. In these applications how are landmarks extracted? The Durrant-Whyte paper does not mention it and I could not find an end-to-end demo project that includes landmark extraction.
Usually landmarks are many distinct, salient features like blobs or corners within an image/frame. Salient features in computer vision are an art in itself. There are dozens of different approaches to extract, describe and match such features (you obviously need to recognize them in different frames).
Wikipedia has an overview and here you see a video of a practical SLAM implementation running on a mobile phone (a little bit of advertising for an excellent university:).
In case of images, they uses feature matching algorithms like SURF or ORB. ORB SLAM, one of the most popular open source slam solution uses ORB feature extraction only.
In vision-based applications, firstly features (interest points) are detected. The feature description step detects salient features only such as corners, blobs etc. and it doesn't make sense alone. Feature descriptors identify each feature in the scene. From this moment, you can choose the ones you want as landmark, keeping in mind your SLAM algorithm.
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I need to load and store 3d models in my project and render them in an OpenGL scene. I can choose type of models to be exported. dwg, max, step and some other formats are available. Just found that OpenGL is low-level API and does not contain any facilities to parse 3d model files. I'm looking for some library/API to translate a 3d file structure into OpenGL primitives (or some other raw data) and store them back in a file with specified format.
For example I would like to load a step file, rotate and scale some objects, and then save modified file.
I think that Assimp could be what you are looking for: http://assimp.sourceforge.net/
C++ 3ds loader:
http://www.spacesimulator.net/wiki/index.php?title=Tutorials:3ds_Loader
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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.