IBL (HDRI) rendering

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3DCGdesign
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kmarius wrote:I used maps, but no shadows appear. What am I doing something wrong? I have tried several hdr IBL and maps. I tried climbing sIBLedit intensity lights but I had no luck. Sorry for my English.
could this be the reason?
http://www.thearender.com/forum/viewtop ... 589#p27589
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3DCGdesign
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naudofr wrote:Hi,

I would like to understand the meaning of the wrapping methods.
I didn' t find the answer in the manual, neither on the forum.
I tested the 6 methods with the same image and I got some ideas but too vague and a lack of depth understanding.

So what are they doing ? Spherical, Hemispherical, Angular probe, Center, Tile and Fit.

Thanks for your answer.
Spherical wraps the whole image around the scene as if it were painted on the inside of a large sphere surrounding your scene.

Hemispherical only maps the image to half of a sphere that is a dome over the top of the horizon line around your scene

Angular Probe uses the projection used in any HDR that says "probe" in the name of it. otherwise, if you load a probe into a spherical projection, then it will have a black hole in the top or bottom. Angular Probes usually have a thumbnail that is a circle of the image with the 4 corners black.

Center Tile and Fit... I've not played with in Thea, but if they are like in Kerkythea, do not use them, they do not contribute to lighting of the scene, nor to reflections, they are only for putting a 'dumb' background picture behind your object... they are what I would consider 'legacy' items there from ages back.
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naudofr
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ok, it's clear now.

Thanks 3DCGdesign ;)
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cekuhnen
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out of curiosity

why do you use a blurred hdri file for illumination and not a more detailed image?
does the blurring prevent noise in the rendering because the light and color
emission is more soft / diffuse as well?

Claas
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blair
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I would like to understand this better also.
Gateway:Pentium(R)4 CPU 2.53GHz,2.52GHz, 1.0GB RAM,XPpro 32bit SP2, Nvidia GeForce 6600. Know a little SketchUP v7pro and a little Photoshop CS. All helpful thoughts and suggestions will definately be appreciated.
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sepo
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cekuhnen wrote:out of curiosity

why do you use a blurred hdri file for illumination and not a more detailed image?
does the blurring prevent noise in the rendering because the light and color
emission is more soft / diffuse as well?

Claas
I believe it is the case...certainly the case for Vray.
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bmscmoreira
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I believe it's for speeding things up. For illuminating purposes, a small and blurred hdr is enough. For a background map, a clear and high resolution is needed; for reflection/refraction, something in between. More about this here: http://www.hdrlabs.com/sibl/how_it_works.html

And a great tutorial:
http://www.thearender.com/forum/viewtop ... =54&t=2110
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saurus
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It would be nice if Thea could load an .ibl file format and put all parts in right places.
I don't think this is hard to implement.
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blair
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Using an IBL, with sky, seems to make a valuble differance to lighting a scene but I have some questions. When rendering with IBL+Sky, specifically for an exterior, is it best to use the IBL in the "Image Based Lighting", "Reflection and Refraction Mapping" slots or would, in certain cases. only some of the slots mentioned be used. For the situation I am referring to in the "Background Mapping" slot an IBL is not being used. If IBL's are used in the slots mentioned above do you try to get the sun in the same position as it would be for the seperate sky "Background Mapping" actually used, by using "Rotation" for each IBL location or just bring it in and accept the default "0" rotation? Also, no matter how it is done, at each slot do you accept the defaut "Intensity" of "1" or perhaps decrease it to .75 or .50 etc. depending on the scene?
Gateway:Pentium(R)4 CPU 2.53GHz,2.52GHz, 1.0GB RAM,XPpro 32bit SP2, Nvidia GeForce 6600. Know a little SketchUP v7pro and a little Photoshop CS. All helpful thoughts and suggestions will definately be appreciated.
hammer
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Blair In my experience you want to try to position the sun manually to the place in the sky your IBL occupies. YOu can also rotate the IBl to match the location of your sun. I would use all of the IBL slots and add the sun as a light. You can play with the intensity quite a bit. I often have a hdr of say 3 and a reflection of say 6 same with refraction. This is where your own judgement of what looks right comes in. Now having said that I would be curious if there are any hard rules to the ratio of intensity the different IBL slots.
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