How do I make an HDRI?

[davdud101]

 Yo, everyone. I'm participating in the latest Anim8or Challenge on these forums. for purposes of not wanting to do a ton of ART rendering, I've decided to take the easy road and use a simple Environment map (not even cubic, a simple single-image hdri photo).
So I'm wondering... Once I make my complete environment, I'm going to want to turn it into an HDRI photo. how would/could I do this? WOuld I set up 4-8 cameras in a circle, then make one large, stiched-together photo? Or what?

[benzjie]

a HDRI is a global of which you can adjust the intensity and thus the amount of light it admits in a renderengine. What you want to make is a panoramapicture...you can use 1 camera or 2 take the pictures and stitch them together in any graphics program ( use a tripod) There are free, real, HDRI for download on the internet.

http://www.3dm3.com/forum/f123/free-hdri-images-5982/

[dwsel]

If I understood well... you're trying to render your scene's environment and then put inside the environment map your animated model for quicker rendering, right?

I know a very good source of knowledge about rendering hdri environment maps (showcasing and comparing flaws of different rendering methods). Although it's a bit Bryce-centric most of the informations apply to all software.
http://www.horo.ch/raytracing/how2hdrshop/sys/index_en.html
http://www.horo.ch/raytracing/how2hdri/sys/index_en.html
http://www.horo.ch/raytracing/how2pano/sys/index_en.html
http://www.horo.ch/raytracing/how2mb/sys/index_en.html

In the meantime I'm trying to render such a hdri from Anim8or scene. I'll post the results soon

[Raxx]

In your case it would probably be easier to render the six cubic environment maps rather than stitching it all together using a separate program. If all you're doing is using it for reflections in an environment map, that would be the best way to go. Simply render the left, right, forward, back, top, and bottom images and put them in the proper fields in Anim8or. Same result, one less step.

[dwsel]

Quick sphere map test, as promised.

[davdud101]

Thanks everyone for all this information! Some of these ways wouldn't necessarily work... not tocall anyone out, but...) Raxx, your way doesn't seem to, as the viewport would look at the whole model from the side rather than from the center of the model. It would certainly work if I used a camera, however. Also, I don't know why, but I feel like having 6 different files would be a little more challenging as far as getting positioning, accuracy, and much more... I don't know, though, as I haven't really ever mseed around with cube-based enviro maps.

Yo, benzjie, those are some great pano's. I may be able to use a couple in future projects, thank you for the link.

Thanks, dwsel, for the nice tests! Hopefully I can adopt one of your methods.

[Raxx]

*sigh* I remember the good ol' days when making your own cubic environment map within anim8or was still hip.

It's pretty easy, and unless I'm totally misunderstanding what you're going for (a reflection map), it's functional.

Place the camera wherever you want (preferrably in the center of the object that the map will be applied to, then hide the object), then render all six directions at a 1:1 image ratio, and 90 degrees FOV. Rotate the side images 180 degrees, then load 'em up as the environment map for that object's material. The results are seamless, and doesn't even require an image editor (the rotating can be done with Windows preview app).

[davdud101]

Oh. It's really thas simple? Well then, Raxx, perhaps this is the best solution. Another good reason to use the cube-based is that in a standard 360-degree panoarmic image, the edgeds loose soooo much value. Thanks, I'll give it a try!

[lppena]

Could something similar be done using transparent materials in Anim8or? Then you just render the scene, and you'd end up with a similar effect. You could add lighting and other effects in the scene editor I would imagine?

[Raxx]

Basic transparency in Anim8or is just transparency with no distortion caused by the material in relation to the geometry. Also, it is non-reflective. To achieve any sort of reflection of the environment in Anim8or using just the built-in materials, the Anim8or Ray Tracer would have to be used. ART is slow, a bit buggy, and time-consuming, so using the scanline renderer is the preferred method when time and ease-of-use is preferred.

[davdud101]

Oh, now I get what Leroy was getting at... Using ART and IOR to render a real refraction map. Which is kind of the backwards process of what I want to do.