CGTechniques.com 
Christian Bauer 8/04


It was three years ago, when i wrote a Tutorial about using a serie of fisheye images to create an hdri skydome for lighten a 3d scene. The idea was really simple, because a fisheye capture horizontal and vertical 180 when you hold it stright, but when you turn it around and look into the sky it captures the full 360 horizont and 180 vertically.
I used mkhdr.exe to generate hdr images, but after a while i started to use hdrshop and i also changed the way i generated my hdri skydomes.

This Tutorial is a more actual tutorial, but still based on the original idea of http://www.cgtechniques.com/tutorials/hdrenviroment.php

You need a serie of fisheye images from a digicam like the CP990.A serie of LDR fisheyeimages

Open Hdrshop and assamble the hdr images. Don't manipulate them in photoshop like in my older tutorial.

You now have an Hdr Image. Drag your mouse over the image. A Fence will appear. You can manipulate the fence by drag the horizontal or vertical borders to the border of the fisheye.

Select the area of the fisheye by draging the mouse

Go to the image menu and crop the image.

Crop the image by image-> crop

Your image is ready to transform now. Transform from *Fisheye closeup* to whatever you need. You have to rotate the fisheye (remember we look in updirection) .So open the transform dialoge and enter "-90" in X direction.

A fisheye is a Mirror closeup and we looked in updirection

There we have the final Spherical panorama.

transformed fisheye

The result can be optimize by changing the whitebalance:
Select an area of white color in your image ...like a white wall. It can be in a darker area of your image. Now go to the image->Pixel->White-Balance Selection

Select a white area and use whitebalance selection

Now press + until the image have the mood of the RL scene. It's not important what the sky will do, but it's more important how buildings and darker areas looks like . With Strg+"0" this exposure will be the default brightness.

exp_correction.jpg

So this is the final skydome tutorial for poor people who use standard cameras/lenses and comon software like hdrshop.

btw, there is a siggraph paper on debevec.org available which describes a similar (but more science) way to Direct HDR capture of the sun and Sky.
You see... this is a really smart and fast way to capture real enviroments for use in virtual enviroments. If you think the range is not high enough for your need then have a look at my "synthesise hdri" tutorial where i pointed to a solution with photogenics. This solution sounds maybe like a cheat for some of you, but it gives very similar results.

chris

 

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