How large does environment maps need to be?

[thomthom]

I was playing around with a scene and thought I'd try the mapping method described by Micha http://asgvis.com/index.php?option=c...0&topic=2320.0

I found a picture on Flickr, http://www.flickr.com/photos/joshsom...54063/sizes/o/ which I thought would work.

I placed a V-Ray infinite plane, applied a texture with the image as spherical environment map.

However, it becomes very pixelated, nomatter what I try. Does it need to be much much bigger, or am I doing something wrong?

[dalomar_cg]

Re: How large does environment maps need to be?

The answer is VERY large. Most HDRS that you find on the web will not really be @ high enough resolution to get things without being pixelated. You can mess with them yourself, but usually that doesn't really fly with HDRs unless you got the ability to edit them, which requires HDRShop or something else.

[thomthom]

Re: How large does environment maps need to be?

Is there any good resources out there for environment maps?
And what kind if equipmen is required to create your own?

I found PhotoShopping the background into the picture afterwards worked somewhat ok. Thought, I had trouble getting the shadows in.
I added the Shadows to the VFB channels, but they where only 2bit black and white. I had hoped for full alpha channel or at least grey scale.
And the perspective in the scene has a much higher view angle so the perspective become a bit weird.

[Travis Serio_cg]

Re: How large does environment maps need to be?

did you apply the map to the Infinite plane? Maybe I understood that wrong. If you did you should note that the Infinite plane should never be image mapped as it never ends meaning the map gets stretched on and on. Sorry if I misunderstood you.

[dalomar_cg]

Re: How large does environment maps need to be?

I added the Shadows to the VFB channels, but they where only 2bit black and white. I had hoped for full alpha channel or at least grey scale.

All channels will be calculated at with full float values. The Shadow channel is no exception, so if you're not getting a full greyscale image (as you see it) the that would be a bug.

[thomthom]

Re: How large does environment maps need to be?

I've attached the Shadow channel I got.
I saved the render as BMP files, and all the channels where 8-bit images. But as you see the shadow image only had pure black and pure white data.

@Travis Serio: The texture applied was mapped to the environment, not to the mesh of the plane itself, so the size of the plane has no impact. You get the same result from a regular plane.

[thomthom]

Re: How large does environment maps need to be?

Just for reference I attached the RGB channel of the render as well.


I just noticed that there's a "Raw Shadow" channel availible. What the difference between this and just "Shadow" channel?

[dalomar_cg]

Re: How large does environment maps need to be?

I assume thats with the physical camera...in that case it may be something with it being a direct light (no soft shadows) that causes it to be so crisp. Remember that the shadow channel isn't referencing the environment lighting that "brightens" up the shadows...its calculated as if you had the environment off (maybe thats how raw shadow differs, I'm not sure). Also, because the shadows are at such an oblique angle, there's very little chance for AA to smooth that edge out.

[thomthom]

Re: How large does environment maps need to be?

hm... The thing is that in the render you can see a hole in the shadow, while in the shadow channel it's solid.

I guess I'll have to do some more test to see how it behaves.

[dalomar_cg]

Re: How large does environment maps need to be?

I'd suggest doing more tests in situations that don't involve the sun and have a minimal environment. That will allow you to see a bit more correlation between the render result and the shadow channel