This Tech Talk was very different than every other one I’ve given as it really wasn’t about any technology at all. In essence, it was a talk about everything I wish I knew when I started at RIT and moreover, it’s the graduation speech I couldn’t give

In the talk I went over over project management tips, personal information management tricks, tips for leading a happy life as a student and generally anything I’ve found in the past few years I’ve found to be really useful – in essence, everything I’ve learned the hard way so you don’t have to

Video: http://www.chriscowdery.com/talks-data/hackinglife/video

Slide Deck (with notes): http://www.chriscowdery.com/talks-data/hackinglife/hacking-life-with-notes.pdf

Links referenced in talk:

• http://chriscowdery.com/go/fav-quotes
• https://github.com/chriscowdery/team-rage
• http://chriscowdery.com/go/late-night-mix

These past two weeks have been an interesting few for my ray tracer. It began with this:

private IEnumerable<ISect> Intersections(Ray ray, CGScene scene)
{
return scene.AllObjects
.Select(obj => obj.Intersect(ray))
.Where(inter => inter != null)
.OrderBy(inter => inter.Dist);
}

Here are some sample images of the .NET version. Check it out!

Checkpoint 6

Different Programmatic Shader

Different Light Position and Color

Wood Texture Mapping

Anyways, this project certainly has been a learning experience, and I got some cool images to show at the end of the day. Not bad!

Assignment 5

Alas, here it is! Reflections!

Good news is that I have reflections working the way I want, bad news is that I’ve incurred a lot of technical debt in the process so I’ll be working some refactoring this weekend. Truth be told, I’ve been working on it for a while (another completely codebase), but I haven’t had the time to devote to polish yet. I have some extra time this weekend, so I’m planning on going to town and getting the other codebase back up to speed. More to come on that soon

I was encountering an issue earlier where Wordpress wasn’t letting me post updates, but alas, that’s all fixed and the site is back up and running. Whoo hoo!

In other news, I just got an apartment in Pittsburgh this past weekend, so that’s really awesome! I’ll be a mile away from Apple Pittsburgh, and it’s in a great area of town. Here are some photos of the place (although the photos contain the current residents’ things ): http://www.facebook.com/media/set/?set=a.10150496899807541.364551.505467540&type=1&l=9e0ef01420

Also, I was named GCCIS College Delegate recently too, so I’ll be speaking at commencement! I’m really excited about this and it’s really huge. I can’t wait!

Remember how last week’s ray tracer was in OpenGL and GLUT? Boy, that was a mistake. Although I got the end result I was hoping for, I really shot myself in the foot for future increments. The primary reason for this was that I was attacking the problem the wrong way. Although I was able to rasterize an end result that looked visually correct, it relied on the OpenGL and GLUT calls to rasterize the end result, and I found myself having to write some janky and nefarious workarounds to make it work with GLUT that just (for lack of a better phrase) made me feel dirty.

So, on Tuesday night I decided something had to go and scrapped everything and began anew. This time, I’m taking the high road and writing everything from scratch in C++. This release has its own geometry classes (CGRay, CG3DPoint, CG3DVector, CGNormal, CGMatrix, etc.) and all that business is happening in an O-O way.

I’m happy with how it’s coming together now, and the design I’m very satisfied with. Moreover, the extra push I had to get this release working The Right Way™ will help grease the skids in the future.

Here’s a couple other improvements which I feel will help me in the future:

• The scene is now centered at the camera at 0,0,0. Now everything can be positioned relative to the camera in absolute space, which gives me some cleaner numbers to work with when manipulating objects.
• Ability to do supersampling.

Here’s the default output image:

Here’s a supersampled image, notice that it looks a little bit crisper (look closely):

I did not have time to add an extra object type for this release due to time constraints, but I’ll be working on that in the future, perhaps in terms of an .obj or .dae loader.

I’m also looking into deferring some of the processing to the GPU (CUDA) to increase rendering performance, and I plan to look at that over the break. I’ve installed the SDK and I’m dabbling with that now, and I hope to have some elements of GPU-accelerated rendering for the next release.

At any rate, there’s lots of cool stuff happening under the hood! Take a look:

For simplification purposes, a CGShape is an abstract class that (at this point) is either a CGSphere or CGRect.

There’s lots left to do though, so I’m going to capitalize on the break to get some extra polish done on the ray tracer. So far this scene rendered in 0.5 seconds. Not too bad, but I think I can do better!

PS: Every release I have for personal software projects is accompanied by a tagline and a silly image. This release was called “Not What You Expected” because my previous release ultimately had to be thrown out – something I most certainly didn’t expect

Setting up the Scene

In this assignment I began my recreation of Turner Whitted’s famous ray tracer published in his 1980 paper. The assignment was relatively straightforward, but the majority of my time was spent getting the objects to appear as they did in Whitted’s paper. The image I am trying to replicate looks like this:

So, as far as the objects are concerned and the position of the objects… not too bad! Here are the parameters I used to generate the scene:

• Size and location of two spheres:
  • Big Sphere (foreground)
    • X: -1.83
    • Y: 1.1
    • Z: 8.3
    • Size: 1.0
  • Small Sphere (background)
    • X: -0.83
    • Y: 0.35
    • Z: 7.55
    • Size: 1.0
• The size and location of the floor (conveyed by locations of vertices):
  • Vertex1
    • X: -3.0
    • Y: 0.0
    • Z: 10.0
  • Vertex2
    • X: 3.0
    • Y: 0.0
    • Z: 10.0
  • Vertex3
    • X: 3.0
    • Y: 0.0
    • Z: 0.0
  • Vertex4
    • X: -3.0
    • Y: 0.0
    • Z: 0.0
• The location and parameters of your light source:
  • X: -1.5
  • Y: 9.0
  • Z: -10.0
• The location and “lookat” of your camera:
  • Eye
    • X:  -1.65
    • Y: 0.9
    • Z: 11.2
  • Center
    • X: -1.675
    • Y: -0.005
    • Z: 0.65
  • Up
    • X: 0.0
    • Y: 1.0
    • Z: 0.0

The talk went over very well and afterwards we all made a bacon detector, and had some fun with optical flow.

The slide deck is available here [PDF] if you’d like to see it. Thanks to everyone who came!

The primary notion behind APHOG is that it first does a coarse-grained parts-based detection to suggest possible areas of interest. In this case, we were searching for hands, torsos, faces, etc.

Once the algorithm finds an area that had these features, the algorithm knew (approximately) where a body would be in relation to the feature found. For example, if a head was found, the body likely be below the detected head.

APHOG detecting the possible features of pedestrians (red bounding boxes) and suggesting possible areas of pedestrians (blue bounding boxes)

This allows the the algorithm to perform a full holistic detection (using a series of Histogram of Oriented Gradients – referred to as the “pyramid”) in designated areas of interest – which is a huge performance (and accuracy) win. We feel that it is an improvement over conventional holistic algorithms that scan the entire frame at many zoom levels and parts-based detections that have to run complex logic to determine if the geometry of detected features are connected in such a way that could be a human shape.

If you’re curious to see more how it works and the gory details (and see it in action), please see the links below!

• Final Presentation [PDF]
• Research Paper [PDF]

The iOS Tech Talk this past Thursday was a smash hit! Not only did the lab overflow with people, we covered a lot of ground with Objective-C, Xcode, Interface Builder, Cocoa Touch and parts of the iOS SDK.

Bittersweet news is that the room was so packed we couldn’t squeeze a video camera in there. So the best I can offer everyone is the slide deck as well as the sample code we wrote together. I have both an annotated version of the slides with my speaker notes, as well as a pure image form. Links for these items are at the bottom of this post.

However, since there was so much interest, I plan to host a series of Crash Courses on advanced topics in iOS as well as OS X programming such as Grand Central Dispatch, multitouch gestures, OpenGL ES, consuming network services and many more. More to come on this development soon, but if you’re interested in taking a Crash Course, please indicate what you’re interested in at the form located here.

Also, as promised, for those of you looking for more information

And as always, if you have any questions or feedback, please don’t hesitate to let me know. Thanks for everyone who came and made the night a great success!

Downloads

Source Code
Slides with Notes
Plain Slides