Categories
3d Augmented Reality graphics vision

Augmenting Images with Blender 3D 2.9x

augmenting KITTI image with a 3D car

Trying to demonstrate how to do data augmentation on the KITTI stereo dataset, I found myself diving (too deeply) into Blender 3D.

What I set out to do is add a 3D object to an unsuspecting image from the KITTI dataset, to show that one way to get more training data is by synthesizing. I just put a 3D object in front of an image (say a 3D plane with the image as the texture) and done ✅ – I’ve augmented the image. Turns out it needs a bit more of Blender trickery. This is the real reason for this post.

Categories
graphics opencv python

Packing Better Montages than ImageMagick with Python Rect Packer

ImageMagick has a built in Montage creating tool. It’s good enough for casual montaging, but it’s definitely suboptimal for packing varying size images.

Categories
graphics opencv programming python vision

Cylindrical Image Warping for Panorama Stitching


Hey-o
Just sharing a code snippet to warp images to cylindrical coordinates, in case you’re stitching panoramas in Python OpenCV…
This is an improved version from what I had in class some time ago…
It runs VERY fast. No loops involved, all matrix operations. In C++ this code would look gnarly.. Thanks Numpy!
Enjoy!
Roy

Categories
3d Augmented Reality code graphics opencv python video vision

Projector-Camera Calibration – the "easy" way

First let me open by saying projector-camera calibration is NOT EASY. But it’s technically not complicated too.
It is however, an amalgamation of optimizations that accrue and accumulate error with each step, so that the end product is not far from a random guess.
So 3D reconstructions I was able to get from my calibrated pro-cam were just a distorted mess of points.
Nevertheless, here come the deets.

Categories
code graphics opencv python vision work

Revisiting graph-cut segmentation with SLIC and color histograms [w/Python]

As part of the computer vision class I’m teaching at SBU I asked students to implement a segmentation method based on SLIC superpixels. Here is my boilerplate implementation.
This follows the work I’ve done a very long time ago (2010) on the same subject.
For graph-cut I’ve used PyMaxflow: https://github.com/pmneila/PyMaxflow, which is very easily installed by just pip install PyMaxflow
The method is simple:

  • Calculate SLIC superpixels (the SKImage implementation)
  • Use markings to determine the foreground and background color histograms (from the superpixels under the markings)
  • Setup a graph with a straightforward energy model: Smoothness term = K-L-Div between superpix histogram and neighbor superpix histogram, and Match term = inf if marked as BG or FG, or K-L-Div between SuperPix histogram and FG and BG.
  • To find neighbors I’ve used Delaunay tessellation (from scipy.spatial), for simplicity. But a full neighbor finding could be implemented by looking at all the neighbors on the superpix’s boundary.
  • Color histograms are 2D over H-S (from the HSV)

Result

Categories
code graphics opencv vision

Laplacian Pyramid Blending with Masks in OpenCV-Python

lpb

A small example on how to do Laplacian pyramid blending with an arbitrary mask.
Enjoy
Roy

Categories
graphics

Visualizing yearly submission deadlines with d3v4

Screen Shot 2017-06-20 at 12.01.33 PM
As an assistant prof. I’m always chasing my tail with proposals and paper submission deadlines. So I created this tool to help me keep track and plan.

Categories
3d graphics

Model and render a folded paper with FreeCAD, Blender

Hello,
I created a little video tutorial to model and render a folded piece of paper for a project I’m working on…
Here it is, enjoy!

Categories
3d code graphics gui opengl qt

WTH OpenGL 4? Rendering elements arrays with VAOs and VBOs in a QGLWidget

I spent an entire day getting OpenGL 4 to display data from a VAO with VBOs so I thought I’d share the results with you guys, save you some pain.
I’m using the excellent GL wrappers from Qt, and in particular QGLShaderProgram.
This is pretty straightforward, but the thing to remember is that OpenGL is looking for the vertices/other elements (color? tex coords?) to come from some bound GL buffer or from the host. So if your app is not working and nothing appears on screen, just make sure GL has a bound buffer and the shader locations match up and consistent (see the const int I have on the class here).

Categories
code graphics programming video

YUYV to JPEG conversion with libjpeg

Sharing a small libjpeg snippet.
Some SO questions about it have only partial snippets:


Enjoy!
Roy