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axefrog

Member Since 08 Apr 2011
Online Last Active Today, 09:44 PM

Topics I've Started

Limit Theory update #21

13 December 2014 - 11:01 PM

Josh Parnell's work is seriously awe-inspiring. Check out his latest:

 


Graphics programming theory help - trade for web dev help/advice/work?

04 December 2014 - 11:59 PM

Hey all, I really want to gain some expertise in graphics programming and am trying (currently going through Real Time Rendering, and calculus on Khan Academy), but I am finding that I hit roadblocks where if I just had someone I could have a conversation with to help me clarify things, I'd be able to move a lot faster and skip over some of the frustration I'm experiencing. I can post individual questions on here I guess, but it's really hard to get the clarity I want and hone in on the answers to the questions I have without having that opportunity to have an actual back and forth conversation with someone who is experienced and knows what they are doing.

 

So here's my offer, if anyone is even remotely interested. I have been doing full-stack web development my entire career (1998+). I know design, I know typography, I know advanced JavaScript and CSS like the back of my hand. I know cross-browser development and responsive design. I know the .Net stack (C# in particular) very well, having used them since 1.1 in 2003, and I am well-versed in various database technologies. I feel very comfortable with general problem-solving, system design, planning and architecture. If you need any assistance or advice in any of these areas, I'd love to get you on Skype and trade some knowledge, or maybe help you out a bit with tuning up your website's design or functionality (within my skill set) in return for a bit of just general help understanding the theory. I actually really enjoy helping others learn in areas  I have skills in, so trading some knowledge, or just being generally available for when you have questions would be no problem at all.

 

My trouble area right now is understanding lighting fundamentals. I'm getting there, but it doesn't feel intuitive at all yet, and I'm having trouble understanding some parts of the radiometry section of Real Time Rendering (if you have this book and understand its contents, that's a big plus).

 

At the very least it'd be nice to have a few contacts in this space that I can bounce stuff off of. Skype and Google Hangouts are my primary means of communication. Let me know.


Recommend a book on differential geometry

28 October 2014 - 12:56 PM

I'm currently partway through learning calculus and linear algebra for graphics programming (using books I bought on Amazon), but it's been brought to my attention that I really should add differential geometry to the list.

 

Can anyone recommend a good book on differential geometry before I try my luck with Amazon book roulette?


A radiometry question for those of you who own Real Time Rendering, 3rd Edition

26 October 2014 - 12:47 AM

I'm a bit confused by the following diagram (7.4) on page 207 of Real Time rendering, 3rd Edition:

 

2014-10-26_1634.png

 

The text before and after I think makes a few assumptions and doesn't quite explain what I'm looking at well enough. What I understand:

  • dw is the change in steradians/solid angle w
  • dA is the area irradiated by the light ray with respect to dw
  • n is obviously the surface normal
  • The orange line is clearly a light ray

Why am I confused? The light ray is apparently hitting a surface (hence the surface normal pointing away from the surface), and the angle depicted is the angle between the ray hitting the surface, and the surface normal. But what is the circle at dw indicating? My understanding was that the solid angle is easily visualised as a cone apexed at the light source, with the circle representing a patch surface on a sphere enclosing the light source. Why then is that circle in the diagram apparently situated at the light source? It seems to me that the cone in the diagram should be facing the other way.

 

p.s. I hope the authors don't mind me displaying this diagram. I will remove it and replace it with my own hand-drawn version if requested to do so.


With regards to texturing, what is "linear space" and "nonlinear space"?

24 October 2014 - 12:56 AM

On page 164 of Real Time Rendering (3rd Edition) there is the following passage:

 

"For textures encoded in a nonlinear space (such as most color textures), ignoring gamma correction when filtering will modify the perceived brightness of the mipmap levels. As you get further away from the object and the uncorrected mipmaps get used, the object can look darker overall, and contrast and details can also be affected. For this reason, it is important to convert such textures into linear space, perform all mipmap filtering in that space, and convert the final results back into nonlinear space for storage."

 

It's entirely possible that linear and nonlinear space were described at some earlier point, but I'm damned if I can find where. Please feel free to enlighten me...


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