Subscribe to GameDev.net Direct to receive the latest updates and exclusive content.
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.
Posted 30 April 2009 - 02:41 AM
Posted 30 April 2009 - 05:27 PM
Posted 01 May 2009 - 01:13 AM
Quote:
Original post by crowley9
> 1) For the cos(theta) term. As theta increases, cos(theta) decreases,
Yes.
> thus L increases.
No. It is divided by the cosine term, so as cos(theta) decreases, L increases.
Quote:
> Does this imply radiance at a grazing angle is larger than radiance aligned with the surface normal?
The opposite - I hope this helps you visualize it better.
Posted 01 May 2009 - 04:09 AM
Quote:
Original post by rumble
1) For the cos(theta) term. As theta increases, cos(theta) decreases, thus L increases. Does this imply radiance at a grazing angle is larger than radiance aligned with the surface normal? And at theta = PI/2, L blows up?
Quote:
2) I am still unsure how to relate the differential solid angle and differential area in the same formula. I can accept that dPhi/dw is the radiant intensity. But further divide it by the projected differential area I can not visualize as easily.
Posted 01 May 2009 - 09:11 AM
Quote:
That's right. Radiance gives the transmitted radiant power through the given solid angle per unit of projected area. That is why you need to divide by the projected area given by cos(theta)*dA. At a grazing angle the projected area approaches zero, hence the radiant power per unit of projected area approaches infinity.
Quote:
The reason why you need to divide by the projected differential area is because it's size can vary for the same solid angle based on [bold]distance[/bold].
Posted 01 May 2009 - 03:11 PM
Quote:
Original post by rumble
1) For the cos(theta) term. As theta increases, cos(theta) decreases, thus L increases. Does this imply radiance at a grazing angle is larger than radiance aligned with the surface normal? And at theta = PI/2, L blows up?
Posted 01 May 2009 - 08:54 PM
Quote:
Original post by rumble
Well, that's not what the formula for radiance predicts? Like we both mentioned, since the cosine term is being divided, L increases as theta increases to approach a grazing angle.
Hence my confusion.
Posted 02 May 2009 - 02:30 AM
Posted 04 May 2009 - 07:14 AM
Posted 05 May 2009 - 10:00 AM
Quote:
Original post by rumbleI was thinking about the sampling of radiance in the scene and how come they are not larger at grazing angles. Perhaps the cosine term in the integrand is ommitted because it cancels with the cosine term from the incoming radiance?
Quote:I searched for radiant intensity
And David Neubelt, how did you find that link. I searched 'radiance', 'radiance optics', and similar terms but this nice page does not show up in the first and many pages of the results.
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.
GameDev.net™, the GameDev.net logo, and GDNet™ are trademarks of GameDev.net, LLC.