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Cube or Sphere setting for HDRI?
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Cube or Sphere setting for HDRI? // Archive: Tech Forum
Post by ed_baker // Jun 2, 2006, 4:49am
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ed_baker
Total Posts: 355
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ts7.1 HDRI with Lightworks engine:
When clicking on the type of HDRI it only shows:
Detect
Panorama
Probe
Cross V
Cross H
Where's the Cube and Sphere? |
Post by splinters // Jun 2, 2006, 5:24am
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splinters
Total Posts: 4148
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I was under the impression that the cube was the V Cross and the sphere was the probe. Then again I have been wrong before...many times.;) |
Post by ed_baker // Jun 2, 2006, 6:31am
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ed_baker
Total Posts: 355
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I was under the impression that the cube was the V Cross and the sphere was the probe. Then again I have been wrong before...many times.;)
Ah, that makes sense. I wonder if that's what it is? |
Post by noko // Jun 3, 2006, 1:33pm
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noko
Total Posts: 684
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In TS7 and manual, TS7 had cube, sphere and probe (which ment angular map). In TS 7.1 probe covers both spherical and angular map and the cube selection was removed (not supported). As far as I know cube did not do anything and was a feature not implimented (basically from within TS you take each camera view (front, left, right, back, top and bottom), render and save, later use this format to bring in that environment without having to render all those objects but place them in an image. Photographs also might have been used this way).
Sphere and Angular map are both probes. So selection doesn't seem to distinguish them now, but calls them probes.
A sphere HDRI uses a shiny ball or sphere and camera takes a picture of the sphere (reflection of the environment) and captures virtually 360 degrees, even the back side. Problem with sphere is the outer edges distort back areas, plus camera is harder to hide.
Angular map helps to capture the environment fully with less distortions and ability to hide the camera. It also uses a sphere but camera takes shots 90 degrees apart from each other and the two are combined for HDRI.
Why sphere have been removed and replaced with just probe (which ment angular map previously) I am not sure. They are different and map differently when used for HDRI lighting. |
Post by Shike // Jun 5, 2006, 1:12am
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Shike
Total Posts: 511
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Correct me if I'm wrong, but I was under the impression that Sphere map was a photo taken from one direction and therefore only covering 180degrees. :confused: Should act like an environment map that always moves and points towards the camera?
Or is Spheremap created by taking pictures from the front and rear of the reflector probe? (180deg between)
I've downloaded the HDRI software but havn't tested it yet :o
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Post by noko // Jun 6, 2006, 6:57pm
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noko
Total Posts: 684
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Mirrored spheres reflect nearly the whole environment. Basically mirror formula says angle of incidence is equal to the angle of refleciton. So rays near the outer edge of a sphere's image have an angle of reflection of around90 degrees, thus their angle of incidence also nears 90 degrees meaning that the rays originate from nearly the opposite (back side) of the sphere from camera view. I didn't know this either until I read "High Dynamic Range Imaging" from the Morgan Kaufmann Series. Great book, a bit technical but comes with a cool CD as well. |
Post by Shike // Jun 7, 2006, 12:47am
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Shike
Total Posts: 511
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Incidence..never thought about that! Nice piece of information you've found for us Noko ! :)
( In school we only did simle mirror calculation for flat mirrors...and I believed that rule applied to everything reflective :o ) |
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