July 21, 2020
This morning I had the feeling I had to improve my reflections in an image for the new Substance Designer Online course.

I know that artists often use softboxes textures to add details in specular areas, but I didn’t want to go with a procedural map or someone else’s photo.

That’s why Giona and I did a quick jump in the new SOA Academy 2.0 green-screen room to take some shots ourselves. The idea is to take multiple exposures photos of a softbox, crop and align them in Photoshop, merge them all in Substance Designer, and produce a 32bit hdr for the Corona or V-Ray light.

However, this isn’t a new idea; we’re not discovering new techniques today, just having fun and trying a new node in Substance Designer to see what we can get from it.

After placing the camera on a tripod, we switched on a softbox and set up the software to take multiple exposures of the same shot. The more, the better, even if we’ve done just 6 (-3 to +3), and the result was excellent.

Custom softboxes

Here you can find a tutorial to do the same (https://petapixel.com/2014/07/16/tutorial-everything-you-need-to-know-about-using-auto-exposure-bracketing/). If you can’t do this step automatically, then manually change the exposure for every shot, but try not to move the camera too much.

Final photos in Raw format should look like this.

Custom softboxes: raw photos

In Photoshop, load them all with File > Scripts > Load files into stack.

It’s a good idea to align them (reducing the layers’ opacity to check it).

Custom softboxes: aligned photos

Let’s crop the canvas with a 1:1 proportion and rescale the image to 2048.
It’s a good idea to rename your layers. Then to export them all automatically, just hit File > Export > Layers to file, pick a folder, and .tiff (not compressed) as the format.

Custom softboxes: cropped photos
Custom softboxes: cropped photos
Custom softboxes: final photos
Custom softboxes: final photos

Drag and drop all the cropped images in Substance Designer and choose “link” in the popup not to import them. Here we can merge the 16bit .tiff in a single 32bit .exr with the HDR Merge node.
In “inputs,” match the number of photos, and “output exposure offset” should be 0. That’s it! From the 2D view, hit the save button and pick .exr as the format.

Custom softboxes: SD
Custom softboxes: SD

In Corona or V-Ray, you can then load the .exr inside the light. If you change the light intensity, the image will run through all the different exposures and produce a realistic effect.

Custom softboxes: Corona
Custom softboxes: Corona
Custom softboxes: look
Custom softboxes: look

As you can see from the render, the reflection got a lot better now.

Custom softboxes: before BEFORE
Custom softboxes: after AFTER

You can download a couple of softboxes we made from here and try yourself!

Happy rendering!

Rob.