Prroblems with HDRi skies

Have been going through tutorials and info on the program and am still having
some difficulty with the HDRi images used as backgrounds in exterior views. The
HDRi skies seem out of proportion (too large) and only a portion of the chosen
sky is seem, therefore, the full effect is not what was intended. Is there a
way to remedy this problem?

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Permalink Reply by Render Plus on July 23, 2010 at 1:01pm

There is some discussion of HDRI skies on our old forum at:

http://nxt.accurender.com/forums/p/1119/4981.aspx#4981

Unless you use a very high resolution HDRI Image, they don't work well for backgrounds.

Probably the best thing to do is use the HDRI skies for illumination, but use a different image as the Background image.

See:

http://www.renderplus.com/wk/Background_Image_w.htm

That way you can get the reflections from the HDRI sky, but get a better background image.

Should we have anymore questions is it best to email you or is there a contact number we can call to get answers quickly?

The fastest way to get help is actually to post the question here on our forum:

That way more of us will see you query, along with other users who can give you an answer. We get emails whenever a topic is posted to the forum.

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Permalink Reply by Render Plus on July 23, 2010 at 1:05pm

"The HDRi skies seem out of proportion (too large) and only a portion of the chosen
sky is seem, therefore, the full effect is not what was intended. "

An HDri Sky is a full spherical image - 360 degrees pf sky, 180 degrees above the horizon and 180 degrees below the horizon. If you are makine a 1,000 pixel rendering with a 60 degree field of view, then you will only see 1/6th of the full image (in width) and 1/2 or less of the image in height, so a 1,000 x 1,000 pixel rendering needs a Sky with at least 1/2 of 6,000 x 6,000 resolution.

I say 1/2 because you can usually enlarge the background image by about 2 : 1 without much loss of quality. So 3,000 x 3,000 would work for the HDRi image, but 6,000 x 6,000 would be better. And for higher resolution renderings, or smaller FOVs you would need even larger images.