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
3d Augmented Reality code graphics Mapping opengl programming Tracking video vision

Bootstrapping planar AR and tracking without markers [w/code]

Years ago I wanted to implement PTAM. I was young and naïve 🙂
Well I got a few moments to spare on a recent sleepless night, and I set out to implement the basic bootstrapping step of initializing a map with a planar object – no known markers needed, and then tracking it for augmented reality purposes.

Categories
3d Augmented Reality code graphics opencv opengl programming qt Tracking video vision

Augmented Reality on libQGLViewer and OpenCV-OpenGL tips [w/code]

You already know I love libQGLViewer. So here a snippet on how to do AR in a QGLViewer widget. It only requires a couple of tweaks/overloads to the plain vanilla widget setup (using the matrices properly, disable the mouse binding) and it works.

The major problems I recognize with getting a working AR from OpenCV’s intrinsic and extrinsic camera parameters are their translation to OpenGL. I saw a whole lot of solutions online, and I contributed from my own experience a while back, so I want to reiterate here again in the context of libQGLViewer, with a couple extra tips.

Categories
3d code graphics opengl programming

Vertex array objects with shaders on OpenGL 2.1 & GLSL 1.2 [w/code]

rect3826Phew. Finally this is working!
I’ve been confined to OpenGL 2.1 and GLSL 1.2 on the Mac since the Qt OpenGL context will not pick up the core OpenGL profile (a big problem on it’s own) and get an OpenGL 3.x and GLSL 1.5… So it’s back to old school GL’ing, but anyway some things are working, albeit they have their quirks.
So for all of you battling the OpenGL 2.1 war, here’s how I made VAOs work with a very simple shader.

Categories
3d code graphics gui opengl programming qt Recommended Software

How I fell for QGLViewer for my Qt/OpenGL projects [w/ code]

While looking for a very simple way to start up an OpenGL visualizer for quick 3D hacks, I discovered an excellent library called libQGLViewer, and I want to quickly show how easy it is to setup a 3D environment with it. This library provides an easy to access and feature-rich QtWidget you can embed in your UIs or use stand-alone (this may sound like a marketing thing, but they are not paying me anything 🙂
This is based on the library’s own examples at: http://www.libqglviewer.com/examples/index.html, and some of the examples that come with the library source itself.
Let’s see how it’s done

Categories
3d code graphics opencv opengl programming vision

Head Pose Estimation with OpenCV & OpenGL Revisited [w/ code]

So I was contacted earlier by someone asking about the Head Pose Estimation work I put up a while back. And I remembered that I needed to go back to that work and fix some things, so it was a great opportunity.
I ended up making it a bit nicer, and it’s also a good chance for us to review some OpenCV-OpenGL interoperation stuff. Things like getting a projection matrix in OpenCV and translating it to an OpenGL ModelView matrix, are very handy.
Let’s get down to the code.

Categories
3d code graphics opencv opengl programming Recommended video vision Website

Structure from Motion and 3D reconstruction on the easy in OpenCV 2.3+ [w/ code]

Hello
This time I’ll discuss a basic implementation of a Structure from Motion method, following the steps Hartley and Zisserman show in “The Bible” book: “Multiple View Geometry”. I will show how simply their linear method can be implemented in OpenCV.
I treat this as a kind of tutorial, or a toy example, of how to perform Structure from Motion in OpenCV.
See related posts on using Qt instead of FLTK, triangulation and decomposing the essential matrix.
Update 2017: For a more in-depth tutorial see the new Mastering OpenCV book, chapter 3. Also see a recent post on upgrading to OpenCV3.
Let’s get down to business…

Categories
3d code graphics gui opencv opengl programming school video vision

Spherical harmonics face relighting using OpenCV, OpenGL [w/ code]

Hi!
I’ve been working on implementing a face image relighting algorithm using spherical harmonics, one of the most elegant methods I’ve seen lately.
I start up by aligning a face model with OpenGL to automatically get the canonical face normals, which brushed up my knowledge of GLSL. Then I continue to estimating real faces “spharmonics”, and relighting.
Let’s start!

Categories
code graphics opengl programming video

A Kinect browser plugin with FireBreath [w/ code]

Hi,
Just reporting on a small achievement, part of a big project: Creating a browser plugin to display the Kinect depth map on screen.
The integration was fairly easy, which leads me to think that both FireBreath and OpenNI/Nite are pretty neat framework that are robust..
So let’s see how it’s done

Categories
code graphics opencv opengl programming school video vision

Identity Transfer in Photographs

Hi!
I would like to present something I have been working on recently, a work that immensely affect what I wrote in the blog in the past two years…
To use it:
Go on this page,
Watch the short instruction video,
download the application (MacOSX-Intel-x64 Win32)
and make yourself a model!
It takes just a couple of minutes and it’s very simple…
This work is an academic research project, Please please, take the time to fill out the survey! It is very short..
The results of the survey (the survey alone, no photos of your work) will possibly be published in an academic paper.
Note: No information is sent anywhere in any way outside of your machine (you may even unplug the network). All results are saved locally on your computer, and no inputs are recorded or transmitted. The application contains no malware. The source is available here.
Note II: All stock photos of models used in the application are released under Creative Commons By-NC-SA 2.0 license. Creator: http://www.flickr.com/photos/kk/. If you wish to distribute your results, they should also be released under a CC-By-NC-SA 2.0 license.
Thank you!
Roy.