Forum: Carrara

Subject: HDRI maps how do I make them?

Graviton opened this issue on Jan 10, 2004 ยท 7 posts

Graviton posted Sat, 10 January 2004 at 9:50 AM

Bryce can export scenes as 3d panorama's but not in the .hdr format, equaly I can download from the web some wonderfull free panoramic images in JPEG but not HDRI. How can I make these images HDRI for use in Carrara? Is there a converter of some kind available? or am I missing something? I'm using a Mac. Cheers, Grav

Anytime I see something screech across a room and latch onto someone's neck, and the guy screams and tries to get it off, I have to laugh, because what is that thing?

mateo_sancarlos posted Sat, 10 January 2004 at 2:08 PM

Attached Link: http://athens.ict.usc.edu/HDRShop/

HDRIshop is one way, but I couldn't determine if it works in OS X without downloading it. From what I read, it's just a matter of converting a "spherized" panorama from 8-bit color to a multiple-precision floating-point color system. The jpeg algorithm is probably the opposite of HDRI. In jpeg, a block of pixels gets 8-bit values from a reference pixel and a fourier transformation, so it's totally unnatural way of describing illumination from a skydome. In HDRI each pixel is independent, and its color and luminance can vary continuously over a much wider range than 256 discrete steps.

sailor_ed posted Sat, 10 January 2004 at 10:06 PM

Though I haven't been through it I would think the tutorial by cckens would be worth a look see. See the thread "Creating HDR Images from LDR Images" in this forum.

cckens posted Sun, 11 January 2004 at 9:05 AM

I apologize to the Mac community at large here at Renderosity. At current there is no Mac version for HDRShop, and I make no claims to know any other software that will do what this one does. There has been some discussion of Virutal PC use with HDRShop as there is only the one executable file, but I cannot vouch for that. Grav, the tutorial in the thread only works for PC (right now at any rate), but the 2nd exercise is using a Bryce panorama, so, yes, it can be done... but only by a PC... :( Mateo, HDRShop does more than convert from just a spherized panorama, but that it can do. It can take a 6 face-image and create the sphere or standard panorama from it. The attached images were all created from the bottom panorama. Ken ![dork.gif](http://market.renderosity.com/~carrara/emoticons/dork.gif)

falconperigot posted Sun, 11 January 2004 at 12:08 PM

Attached Link: http://www.acm.uiuc.edu/siggraph/HDRIE/

There is the HDRIE project, the main aim of which is to make the functionality of HDRShop available as open source and cross-platform. However, at present I think you'd have to be proficient at compiling stuff for the Mac in order to use the source files.

mateo_sancarlos posted Sun, 11 January 2004 at 3:05 PM

It's only a matter of time before there's an OS X version. It might be possible to deform a panorama into a box-map, then stitch it into a spherized image, but I don't know how to use Photoshop to convert the integer RGB data into floating point data, unless the typical HDRI file reads out as plain text (unlike jpeg or other image formats). This means that trying to fake it with a tiff image mapped onto a skydome would result in a dark, washed-out render compared to an actual HDRI.

Graviton posted Mon, 12 January 2004 at 3:16 AM

I Have managed to use HDRShop in Virtual PC to convert a Panoramic Jpeg that I downloaded from the web to HDRI ( I didnt mess with any settings, just imported then exported). These are the results I got when using that map with a GI render. It's a start. A Mac OSX version of HDRshop would rule. Cheers, Grav

Anytime I see something screech across a room and latch onto someone's neck, and the guy screams and tries to get it off, I have to laugh, because what is that thing?