EnvMap + (fake) Sun Tutorial

[juan_irender]

Hi!
This is my own attempt to do a environment + sun scene, an outdoor illuminated one.
I´ve used a 16 bit PNG texture for the environment, since it´s rendered with Indigo 2.2.2.
It´s very convenient to manage as separate light layers the environment and the sun .

Bye!

[madcoo]

Brilliant!!!

[Zom-B]

I prefer to use 16bit TIFF files since Indigo once some time ago did load 16bit PNGs but clamped to 8bit... maybe this issue is sorted out by now.

Anyway... you can still use float 32bit spheric angular images

Get some of these here: http://www.debevec.org/Probes/

Using qtpfsgui you can convert your existing 32bit files to angular or mirror ball and then save as float with HDRshop. Its quite a workaround, and a fix would be more welcome...

Here the code to include the angular image in your scene:

Code: Select all

    <env_map>
        <spherical>
            <path>textures/preview_map.float</path>
            <gain>700000</gain>
            <width>640</width>
        </spherical>
    </env_map>

[juan_irender]

Thanks, Madcoo!
Thanks again, ZomB. I´ll try this workaround .

Cheers.

[juan_irender]

Hi again, ZomB.
I´ve converted an .exr file to angular and saved in .hdr format, then I opened in HDR Shop and save the file in .float format.
Now, I´m exporting the scene from Cinema 4D using Cindigo. But unfortunately, Indigo (2.0.12 or 2.2.2) hangs, as occurs with .exr files, so for now, we have only the 16 bit tiff option for MDR quality environments!

[Zom-B]

Sorry, I totally forgot to give you the code to include the angular float image:

Code: Select all

    <env_map>
        <spherical>
            <path>textures/preview_map.float</path>
            <gain>700000</gain>
            <width>640</width>
        </spherical>
    </env_map>

I updated my previous post too...

[juan_irender]

Hi, ZomB.
Good news, the .exr files can be used on Indigo 2.2.3 inside an env_map statement with the latlong type.
The sintax is:

Code: Select all

    <env_map>
        <latlong>
            <path>Tex\Environ3.exr</path>
            <gain>80000000</gain>            
        </latlong>
    </env_map>

I´ve render the dragon figure using an HDR environment as the only light source in the scene, I´m amazed at how well defined are the shadows produced by the sun of the HDR map.
Bye!

[galinette]

Not sure that the base problem (soft shadows) does not come from the fact that the envmap is not a real HDR (with physically correct dynamic range). The sun pixels should be something like 30000 to 100000 times brighter than other pixels. In that case, I see no reason why indigo should not produce crisp shadows.

Here are example images, rendered with envmap as only light source.

Image rendered with a clear sky envmap from evermotion. The shadows are soft despite the bright sunlight in the image.

After opening the .exr in photoshop and measuring the pixel values in the sun disc and in the sky, it appears that the contrast is lower than it should be. So I correct by manually painting a sun disc with a brush.

Now the shadows are OK. Indigo seems to suffer from sampling problems, though.

This shows that soft shadows in envmaps are not intrinsically due to the use of envmaps, but to the fact that camera generated envmaps have a too low dynamic range (sun pixels too low). These envmaps should be manually corrected for proper contrast in photoshop or computer-generated to have correct light power values in the sun disc.

Etienne

[juan_irender]

Thanks, Galinette . I´ll try with some HDRi, seems to be a common "problem" with such pics.

Bye.

[Pibuz]

I must have read something about this in Bertrand Benoit's (old and superb Indigo user) blog. He showed some workarounds to get sharper shadows working with EXR or HDR images. He stated that it is sufficient to open the file in PS and adjust the gamma slider, or something similar.

here is the link, maybe it's useful:
http://bertrand-benoit.com/blog/2010/02 ... -lighting/

[Frutiger]

I must have read something about this in Bertrand Benoit's (old and superb Indigo user) blog. He showed some workarounds to get sharper shadows working with EXR or HDR images. He stated that it is sufficient to open the file in PS and adjust the gamma slider, or something similar.

here is the link, maybe it's useful:
http://bertrand-benoit.com/blog/2010/02 ... -lighting/

This works brilliantly. A simple and elegant solution. Easily done in Photoshop with an exposure adjustment layer. I feel like I owe Pibuz at least 10 or 15 beers by now.

[Pibuz]

Let's make them 20 and you're done

[pocky]

Thanks for the tut Zom-B! All the the renders are also quite encouraging that this is a great tip. Gonna have a look into it tonight.

I must have read something about this in Bertrand Benoit's (old and superb Indigo user) blog. He showed some workarounds to get sharper shadows working with EXR or HDR images. He stated that it is sufficient to open the file in PS and adjust the gamma slider, or something similar.

here is the link, maybe it's useful:
http://bertrand-benoit.com/blog/2010/02 ... -lighting/

Interesting. Thanks for sharing

[Zom-B]

Thanks pocky

Nowadays this workarround shouldn't be needed anymore since its possible to set a Indigo Sun + a Envmap together in Indigo.

The Question is if exporters supports that feature atm

[Pibuz]

SkIndigo does