HDR 2 EXR + some HDR sites

General questions about Indigo, the scene format, rendering etc...
StompinTom
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HDR 2 EXR + some HDR sites

Post by StompinTom » Thu Aug 23, 2007 1:26 am

in response to the 'EXR' thread below, here are some HDR resources ive found to be useful. these are just off the top of my head:

Paul Debevec's lightprobe gallery
http://www.debevec.org/Probes/

an HDR to EXR converter that i found, havent tried it
http://www.imageconverterplus.com/help- ... r_exr.html

if anyone knows of any other sites for free EXRs or HDRs or any better converters, post them here!


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xrok1
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Post by xrok1 » Thu Aug 23, 2007 4:09 am

thanks guys now we're getting some place :D

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Phr0stByte
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Post by Phr0stByte » Thu Aug 23, 2007 5:12 am

Optionally, you can use exrtools to convert PNGs and JPEGs to EXR format. exrtools is cli only and can be downloaded from OpenEXR's website - linux users: check your package manager, as your distro probably packages it.

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carbon
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Post by carbon » Thu Aug 23, 2007 6:45 am

resave hdr -> exr or exr -> hdr with blender :wink:
http://www.indigorenderer.com/joomla/fo ... 0&start=30

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Phr0stByte
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Post by Phr0stByte » Thu Aug 23, 2007 6:51 am

carbon
Excellent point. exrtools are handy for compositing scenes into photos. You have the base photo and the copy of the base photo in EXR format - that will give you all the realistic reflections of your base photo onto the models.

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jurasek
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Post by jurasek » Thu Aug 23, 2007 6:54 am


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carbon
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Post by carbon » Thu Aug 23, 2007 7:04 am

http://www.sachform.de/download_EN.html
http://www.hdrmill.com/Freebies.htm
http://www.hdrimaps.com/

EDIT #1: a lot of commercial hdr producers have some free hdrs on their websites to download
EDIT #2: would be nice to have another 'free (hires,good quality) textures' sticky thread

neepneep
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Post by neepneep » Thu Aug 23, 2007 7:42 am


jeffr
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Post by jeffr » Thu Aug 23, 2007 12:59 pm


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xrok1
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Post by xrok1 » Sat Aug 25, 2007 3:51 pm

if exr is so great why is it that all i see in this thread are links to hdri files and software to convert hdr to exr? is someone trying to say that an hdr to exr conversion magically adds fairy dust to the exr. if anything this thread supporting exr just proves my point that we need hdr support. :wink:

jeffr
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Post by jeffr » Sat Aug 25, 2007 4:39 pm

EXR was created by Industrial Light and Magic for use with the movie work they do. http://www.openexr.com/index.html


RichardAnnema at Splutterfish gives a good explanation what makes it better.
HDR is a format which allows storage of high dynamic range values in the form of RGBe pairs, compressed through the RLE method, and with a small reserved header.

What this means is that HDR's color fidelity is poor, as the red, green and blue channels all share the same exponent.
OpenEXR, in contrast, stores values in either half or full float per channel. Means it takes up more space if left as the raw data, but its color fidelity is much higher.
Technically its range is lower, but you would be hard-pressed to reach the top of the range.

It also means that HDR doesn't store an Alpha channel. That's pretty major if you want to composite anything.
OpenEXR does store Alpha. And G-Buffers. And any other channel you would like.

And with HDR you can only store so much information about the image in the header. OpenEXR, on the other hand, allows you to store limitless (or a lot, at least) amounts of information and such in string fields.

It's also backed by a lot more companies and products. HDR is fairly niche, whilst OpenEXR is gaining new grounds quickly - discreet added OpenEXR support in Combustion 3, for example - but I don't think it support HDR at all.

There's loads more advantages, but those are the major ones anyway.

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Kram1032
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Post by Kram1032 » Sat Aug 25, 2007 8:14 pm

jeffr wrote:
...And any other channel you would like...
Micropolygondisplaced Exr as sort of a textured emitter, that still allows changes O.o
(Z-depth channel included or something like that)
[caustics affect the exr as well as shadows]

Material-Buffer for reflective stuff {additional caustics +reflected scene } and glass stuff { + refracted scene } O.o.O.o.O.o.O

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xrok1
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Post by xrok1 » Sun Aug 26, 2007 1:10 am

not denying that its better. so is blu-ray, dosn't mean i'll through my dvd's out just yet. i'm saying add something we can use today without the pain (i'm sure converted hdr is not the same as exr anyway). i'm not suggesting to throw away exr support, just suppliment it.

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deltaepsylon
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Post by deltaepsylon » Sun Aug 26, 2007 1:30 pm

imo, there's more pressing things to do with indigo than add in hdr support.
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