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#Actualopengl_beginner

Posted 28 October 2012 - 01:25 PM

Hi guys! Posted Image


This is my very first post on this forum Posted Image


I'm very much new to OpenGL and I'm currently starting my newest adventure in this field - Spherical Harmonics.
The idea I would like to implement it the following:

A user interface (OpenGL or MATLAB), which displays an illumination model and a scene containing synthetic objects.
The user gets to rotate/move/play around with the illumination model and, as a result, the image is rendered under the chosen illumination.



I have read through quite a few previous posts on this topic and googled the web (this is the most relevant project page: Link), but there are still a few open questions.

1) What is the interpretation of a spherical harmonic model - it models the incoming light for each pixel on the surface, i.e. irradiance. And rendering is done based on the outgoing lighting power, i.e. radiance. Is this correct?

2) SH are said to be good for image with only low-frequency components. Why so? Could anyone provide with an example image, which is NOT suitable for SH modeling?

3) Spherical harmonics can be represented using cube maps or spheres. What is the difference - is one representation better than the other? Are there any other options - e.g. triangles, octaeders, ellipses, etc.?

4) Light probes can be used as environments maps (Link). Are there any other options?

5) I came across an excellent tutorial by Robin Green (Link). I also found a nice implementation of it, which I would like to edit: Link
Unfortunately though, I am not quite sure how/where to get started.
Any suggestions?


Looking forward to your response! Posted Image

#1opengl_beginner

Posted 28 October 2012 - 01:24 PM

Hi guys! Posted Image


This is my very first post on this forum Posted Image


I'm very much new to OpenGL and I'm currently starting my newest adventure in this field - Spherical Harmonics.
The idea I would like to implement it the following:

A user interface (OpenGL or MATLAB), which displays an illumination model and a scene containing synthetic objects.
The user gets to rotate/move/play around with the illumination model and, as a result, the image is rendered under the chosen illumination.



I have read through quite a few previous posts on this topic and googled the web (this is the most relevant project page: Link), but there are still a few open questions.

1) What is the interpretation of a spherical harmonic model - it models the incoming light for each pixel on the surface, i.e. irradiance. And rendering is done based on the outgoing lighting power, i.e. radiance. Is this correct?

2) SH are said to be good for image with only low-frequency components. Why so? Could anyone provide with an example image, which is NOT suitable for SH modeling?

3) Spherical harmonics can be represented using cube maps or spheres. What is the difference - is one representation better than the other? Are there any other options - e.g. triangles, octaeders, ellipses, etc.?

4) Light probes can be used as environments maps (Link). Are there any other options?

5) I came across an excellent tutorial by Robin Green (Link). I also found a nice implementation of it, which I would like to edit: Link
Unfortuntately though, I am not quite sure how/where to get started.
Any suggestions?


Looking forward to your response! Posted Image

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