I have a Canon T3i with a Canon EF 50mm f1.4 lens that I use for the gross majority of my day-to-day photography these days. I’ve been using a custom firmware for the Canon called Magic Lantern that provides a some interesting (and useful!) functions. One of them is HDR video. Here’s a beautiful example of what can be done:
I tried my hand at processing the HDR video output and was able to get a reasonably nice tone-mapped video:
After the break, you’ll find how I processed the initial Magic Lantern video using MATLAB and exiftool and tone-mapped the output using Luminance HDR.
I have been working with a 3D blobby object for some of my pilot studies on shape from shading and texture that I would like to 3D print. Back at Rutgers University, we had a MakerBot Cupcake, but now that I am in Germany, I need to find alternatives. I have been looking into getting the 3D object printed using Shapeways.com but there have been a few hiccups along the way, so I wanted to describe my experiences in the hopes that it might help someone else avoid these issues in the future. The object was generated in MATLAB using a simple script (see 3D “Potato” Generation using Sinusoidal Pertubations) and rendered in our 3D environment:
So the question is: What do I need to do to get this 3D object printed at Shapeways? Click through to see the steps that I took to get this 3D model printed economically. Read More
After using my Arduino Fio to make an Arduino LCD oscilloscope, I wanted to try adding a second channel. Using the single channel Arduino FIO LCD Oscilloscope code as a template, I modified the project and added a second channel.
Here’s a short demonstration video of the new two channel project:
Click through the break to check out the code. Read More
It has been 7 years (!) since I posted my PIC18F2550 KS0108 Graphical LCD Oscilloscope code and schematics. I have long since taken the circuit apart, sold my PIC microcontrollers, and moved on in my life (as one can surmise from my most recent posts detailing my graduate and postdoctoral work). However, I still get inquiries about the Microchip PIC oscilloscope, so I decided to recreate it using a simpler setup using my Arduino Fio.
Here’s a short teaser video just to show that, yes, it works (going through a couple different sine wave frequencies, some random noise, etc. just to illustrate it working):
Click through the break to get more information on the setup. Read More
Here are a couple of quick demos, illustrating how blurring a cubic environmental map can lead to a change in the perceived roughness of the surface of 3D rendered objects.
I created a series of HDR cube maps using NVIDIA’s CubeMapGen (currently hosted on Google Code). Starting with the Debevec light probes, I applied a Gaussian blur with increasing kernel size (10°, 20°, 30°, 40°, and 50°), creating 6 cube maps (one for each blur). In the videos, the cube maps have increasing blur from left-to-right, top-to-bottom. Note that I did not tone-map or account for changes in overall exposure (so the specular reflections can appear blown-out, especially for the higher blurs). After the break, you can see the effect using different light probes (and different shapes).
Using the OpenGL/Psychtoolbox framework I have previously described, I replicated this interesting effect. When you play the following movie, a 3D sphere (with sinusoidal perturbations) is rotated. Note the axis of perceived rotation when the object has specular reflections (1st half of the movie) and when the environment map is “painted” onto the surface (2nd half of the movie).
The physical motion of the object is the same in both cases — the object rotates around the vertical axis. When the object only has specular reflections, it appears to rotate around an oblique 45° axis, but when textured it rotates around the vertical axis. After the break, I show similar effects when the object is rotated around the horizontal axis, 45° axis, and when the spatial frequency of the perturbation is manipulated.
Using the building blocks previously described (see 1, 2, 3, & 4) along with some other creative coding, I have been able to generate some nice stimuli. Here is an example of a random shape being spun along the 3 axes while its surface properties (texture, shading, and specular reflections) are manipulated:
2 8 more videos (with different shapes and illumination conditions) after the break. Read More
In order to generate “organic” stimuli with smooth undulations, I needed to systematically manipulate the surface meshes of 3D spheres to create smooth peaks and valleys.
