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View Full Version : How to display bump maps at shallow angles?


mswertfager
07-29-2009, 07:54 AM
I am creating a fly through of a large environment...upon experimenting I noticed that the bump map was disappearing when the camera got really close to the plane...Any thoughts how this can be adjusted short of displacement mapping (bump map is 4096, too large for displacement)?

I am open to creative solutions...

-Michael

See samples below.

At a high angle the bump map shows ruts before the bridge...
http://www.thetell-taleheart.com/images/spt/higher_angle_shows_all_bumps.jpg

However, if I try to fly low through the town and bridge, you can see the bumps disappear in the foreground...Basically, as the camera flys through, the bumps fade out right before they get to the camera.
http://www.thetell-taleheart.com/images/spt/shallow_anlge_causes_bumps_to_disappear_in_foreground.jpg

jeremybirn
07-29-2009, 03:01 PM
Displacement is best of course, if you don't run out of memory it could be good to try. Save your scene before each rendering while you test the tessellation and displacement quality settings for that ground surface.

You might try varying the bump height based on the facing ratio of the surface (sampler info facing ratio out -> ramp v of a ramp texture -> bump height) so you can boost the bump height where you see the surface more head-on, reduce it where you look off towards the horizon.

How you light a bump map matters a lot. Try lighting it more from one side and it might read better.

You could try using the bump map to darken parts of the surface, so the ruts were darker than the high spots, and that should be visible from any angle. Bump maps can enhance a surface, but they shouldn't be the only source of dirt and variation on the ground.

-jeremy

mswertfager
09-24-2009, 08:14 PM
Thank you Jeremy, (BTW, love your books)

Just a follow-up...I went with the displacement maps. While huge, the system handled it quite graciously. Below are some screen shots, displaying the ground displacement in the opening of the video short.

This is about the same frame in the posting above...you can see much more detail in the ground even as the camera approaches it.
http://www.thetell-taleheart.com/images/fly_through_with_treatments_MasterComposition_00845.jpg


Another shot about 2000 frames down on the other side of town, more ground displacement.
http://thetell-taleheart.com/blog/wp-content/uploads/2009/08/moldavia_blue.jpg

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