Getting started with cubemaps?

Joseph Silverman

Hey, in order to have a semi-complete texturing skillset, I really wantto learn a bit more about cube maps.

I seem to understand the theory artwise, and I have a pretty firm idea of how to use a mask for one on a texture and make it look good, but I have no idea where to get or how to make a cubemap in the first place.

I found this, from Ben Cloward, after googling, and I seem to understand the steps he's proposing with hdrshop and the ati cubemap gen:
http://bcloward.blogspot.com/2006_01_01_archive.html

But I'm not sure where or how to get a light probe image in the first place. How is this usually done, by artists? Are you making them in photoshop, or manually cutting together your cubemaps in photoshop, or sourcing them from free images? Taking the photos yourself and going through this whole process?

I really don't know where to start, so, any and all information on getting/creating and using cubemaps would be a great help. Thanks.

fogmann

http://www.debevec.org/Probes/ - there you go, the techy bits, and a place to download some free light probes. But it can become an expensive sport if you want to do the shooting yourself and if you want to be serious about getting great results. You'd need either fisheye lens or chromeball (which you can actually get in garden supply store, and it's much cheaper choice), but then you'll need good camera that will let you shoot at different exposures, and a steady tripod. There is a way to get the HDR image out of single RAW format photo though.
Here's some more tech info on HDR: http://www.hdrsoft.com/resources/dri.html

So basically, when you have HDR light probe, you can use HDRShop to create cubemap, or maps for whichever format you want to use, including sphere or cylindrical maps, if I remember correctly (been a while since I messed with image based lighting).

Eric Chadwick

You can't just stitch together 6 images in Photoshop, unfortunately. Each side of the cube needs 90-degree perspective distortion, without which you get a box-looking cubemap, instead of a smooth 360-degree environment. Not easy to fake by hand.

You can paint one from scratch, or render a CG scene, or photograph the real world, or combine a couple of these to make one.

To paint from scratch, the easiest thing is to use SkyPaint. Costs $85. UI is ugly as hell, but it's basically just a viewer that exports/imports the current view to Photoshop, where you paint what you want. Works pretty well.

CG cubemaps can be made from most 3D packages. There are dedicated 3D landscape/sky proggies that do a good job. Vue D'Esprit, Terragen, etc.

Photos can be done with the mirrorball, or by stitching together a couple shots from a fisheye lens, or by using a standard lens and stitching a whole bunch of shots. Lots of methods, some easier than others...
http://gl.ict.usc.edu/HDRShop/tutorial/tutorial5.html
http://www.panoguide.com/howto/panoramas/spherical.jsp
http://www.johnhpanos.com/360tute.htm
http://www.lightspacewater.net/Tutorials/PhotoPano2/paper/
http://www.ericchadwick.com/examples/tutorials/multi-photo_panoramas_in_max.html

Good luck.

Joseph Silverman

[ QUOTE ]
Just open up an ldr cubemap

[/ QUOTE ]

Where would I get one? Just google, or what?

(fog, eric, thanks, will read through all those links)

Rob Galanakis

The only time you should really need to make cubemaps is when you are actually making a game or level, so the cubemaps are what your actual level looks like. Otherwise, use what is out there, IMO. They're good to make, I know how to make them easily enough, but its pretty irrelevant to actual texturing.

Joseph Silverman

Okay, thanks everyone.

Sa74n

back in the hl1 days i used to create a 360° image in ps that tiles to left and right and map it onto a sphere.. then center the camera in the sphere and render out squares with fov 90 of each direction (front,back,left,right,top,bottom) and fix up the distorted bits on top and bottom in ps. its a quick and dirty technique but it worked out fine for those lowres sky textures in goldsrc
it certainly helped me understand the basics though.