Background's bitmap position/orientation

[40th]

Each time that i use bitmap for environment background i need to render the scene few time till i figure out the orientation of the BG image.
I was wondering if there's a better way to do so. Maybe if i'll know according to what VfSU centering the BG bitmap (SU's model north, X axis and so on).

[dalomar_cg]

Re: Background's bitmap position/orientation

Spherical images get mapped starting from the positive x axis (so to your right if you were looking up the y axis) then get wrapped around going clockwise. This means that the middle of your image will be to your left (again, if you are looking right up the y axis).

I have yet to sit down and specifically figure out exactly how the other projections get mapped.

[40th]

Re: Background's bitmap position/orientation

Ok, thanks.
In SU the axis named by their colors (Red, Green and Blue). I think that the X axis is red. am i correct?

[thomthom]

Re: Background's bitmap position/orientation

Yes, another area where SU just does it own thing. "Red Axis"... mrhmm..

Anyway, yes: Red is X, Green is Y, Blue is Z.

[40th]

Re: Background's bitmap position/orientation

heh yeah...
Alright, thanks.

[fpedrogo]

Re: Background's bitmap position/orientation

I made an image for the webinar that we are going to have on Wednesday. We are going to teach how created your own HDRI on V-Ray. It is for Rhino, but you can apply the same concept on Su.


Best

[sepo100]

Re: Background's bitmap position/orientation

Does anyone have nice sky daylight hdr which looks reasonably sharp to share.

[AcesHigh]

Re: Background's bitmap position/orientation

what I want to understand is VRAYs CUBIC SKY. Plenty of Cubic Skies for download on the internet... none of them fits on VRAY. They all get their bottoms on the sky, the sky on the ground, etc.

[thomthom]

Re: Background's bitmap position/orientation

Sounds like it's reads differently. Just rotate until it's the right way up.

[AcesHigh]

Re: Background's bitmap position/orientation

the ones I have are composed of 6 squares side by side.

the 2 in the middle (number 3 and 4), from left to right, are respectively the TOP and BOTTOM.

[thomthom]

Re: Background's bitmap position/orientation

hm... The ones I've used are laid out in a cross pattern. I htink that's how V-Ray reads them...

[AcesHigh]

Re: Background's bitmap position/orientation

Thom, would it be possible to post an example of the right type of cubic sky? SO I will know what to look for next time, or even create myself out of Terragen and Photoshop?

Btw, are Cubic Skies worth my time? Or should I go with 360 degree sky panoramas?

[thomthom]

Re: Background's bitmap position/orientation

Damien gave some great descriptions to the different environment mappings in this thread: http://asgvis.com/index.php?option=c...0&topic=4766.0

[AcesHigh]

Re: Background's bitmap position/orientation

this is the place where I got the cubic skies
http://www.cgtextures.com/textures.php?t=browse&q=23740

and here I found some info about the different cubic skies formats
http://www.cgtextures.com/content.ph...&name=cubemaps

[dalomar_cg]

Re: Background's bitmap position/orientation

For cubic mappings, I don't know 100% but its an "either/or" type of deal, so here we go. The main thing to pay attention to is the center of the cross, as that determines where all the other squares go. If you're standing at the origin, that center square is either in the positive Y (I'd put my money on that one) or in the positive X direction (but I'm covering my ass). Once you know where that first square lies, then the rest are easy. The one above the center square is above you and the one below the center square is below you. The one to the left of the center square is to the left (where ever that ends up) and the one to the right is (as you guessed it) to the right. The "odd square out" (which should be on the bottom in order to work correctly with V-Ray) is behind you.