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New script: Fake (and fast) HDR – tutorial coming soon

August 14, 2013

In a mixture of self motivated curiosity out of work hours and official studio hours, I wrote a script that fakes the lighting produced by (commonly HDR) environment images.

Its already out and about on GitHub, and you can DOWNLOAD it and test it.

(and don’t forget to report any bugs in my bug tracker!).

In a nutshell, the script creates a spherical light array with lamps that emit colors taken from an image.

It can reduce the render time for Blender Internal by more than half and get a fairly similar result to an HDR image.

In cycles its not very useful at the moment because HDRs are efficiently rendered in Cycles, and the render times are pretty much the same when using the script or the original image.

Fake HDR script interface

A more detailed explanation and tutorial will have to wait a bit, but its coming soon.

Meanwhile I can say that to get good results you need to play with it a bit and try orienting the light array by rotating the empty (that controls all the lights) and play with the light settings (shadow softness and samples, intensity, etc).

Here’s an example of bad and better settings, compared with the original HDR image render:

Render comparisons

I’m still learning how to use it too, so if you get some interesting results and insights, please comment here and let me know!

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2 Comments
  1. Very neat. And being able to modify the intensity and samples from all of them is really usefull. I’ll give it a try. Maybe you can extract color from image, and transfer them to the light’s color, but just letting the brighter ones cast actual shadows. Some time ago, a guy from spain did exactly that, you can see his explanation here: http://www.etereaestudios.com/training_img/hdri_fake/hdri_fake_es_01.htm
    Greetings from Chile

    Antonio Suazo

    • Hi Antonio,
      The color of each individual lamp does come from an image, but the script currently supports only full shadow or no-shadow for all lamps regardless color value (of course you can change anything you want manually).

      Its an interesting idea letting only the stronger lights cast shadow. The script can already discern the strongest light and make that a sun lamp, but what you’re describing is more sophisticated.

      The Spanish guy’s script looks great, seems like a pretty good source of inspiration for future upgrades to my script. It makes a lot of sense to sample the image with a lot of points but to create lamps only in points of interest and that only key lights will cast shadows.

      Cheers

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