[Radiance-general] rendering with environment maps

[Minjung Kim]

Thanks so much for your help, Thomas! That did the trick.

I have two follow-up questions:

(1) When I set the environment map, I also tried including an additional
direct light source. Shouldn't the direct source have illuminated the
Lambertian sphere? I tried setting the intensity of the direct source to be
very high and the environment map to be low, just in case the environment
map was washing out the influence of the direct source -- but still, the
Lambertian sphere rendered completely black. Is it not possible to combine
the environment map with additional light sources?

(2) I want the lighting to be from an environment map, but there to be
additional "environment" that the specular object reflects. More precisely,
I want the specular object to be reflecting a world defined by a texture
pattern, but using the lighting pattern from an environment map. Does that
make sense?

Regards,

MJ




On Mon, Jul 20, 2015 at 11:16 PM, Thomas Bleicher <tbleicher at gmail.com>
wrote:

> You need to throw in an "-ab 1" (or higher) in the rvu line. The HDR image
> does not count as light source and so does not "illuminate" objects with
> the default of "-ab 0". If you had more geometry in the scene you would
> notice that everything is dark. The only thing you see is the HDR image
> itself in direct view or reflected in the sphere (reflection is calculated
> independently of the light distribution).
>
> Regards,
> Thomas
>
>
>
> On Mon, Jul 20, 2015 at 8:41 PM, Minjung Kim <mkim85 at gmail.com> wrote:
>
>> Hi there,
>>
>> I have a question about rendering with environment maps. I set up a scene
>> consisting of two spheres, one completely specular and one Lambertian, lit
>> it with one of Paul Debevec's light probes (
>> http://www.pauldebevec.com/Probes/). The specular sphere is rendering
>> fine, but the Lambertian one is turning up completely black, and I have no
>> idea why.
>>
>> My code looks like this:
>>
>> # make environment map
>> void colorpict uff
>> 9 red green blue uffizi_probe.hdr angmap.cal sb_u sb_v -rx 90
>> 0 0
>>
>> uff glow uff_glow
>> 0 0 4 1 1 1 0
>>
>> !genbox uff_glow boxenv 100 100 100 -i | xform -t -50 -50 -50
>>
>> # make materials
>> void plastic spec # specular
>> 0 0 5 .5 .5 .5 1.000000 0.000000
>>
>> void plastic lamb # Lambertian
>> 0 0 5 1 1 1 0.0 0.0
>>
>> # make spheres
>> spec sphere sph1 # specular
>> 0 0 4 -.5000000 0.000000 0.000000 0.300000
>>
>> lamb sphere sph2 # Lambertian
>> 0 0 4  .5000000 0.000000 0.000000 0.300000
>>
>> I then ran it like this:
>>
>> oconv scene.rad > scene.oct
>> rvu -vtv -vv 10 -vh 10 -vp 0 -10 0 scene.oct
>>
>> When I do this, I get a mirrored sphere and a completely black sphere. To
>> make sure that the problem wasn't with my code, I downloaded this sample
>> code from Debevec's website (http://www.pauldebevec.com/RNL/Source/).
>> When I changed the materials in the .rad file to be Lambertian (lines
>> 182-190 in rnl_scene.rad), the objects rendered as completely black.
>>
>> Has anybody ever run into this problem before? I am using RADIANCE 4.2,
>> on OS X 10.7 (home) and OS X 10.9 (work).
>>
>> Regards,
>>
>> MJ
>>
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>>
>>
>
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