Raytrace/Post processing tips: Making a Material ID layer mask

[Renerabbitt]

Raytrace, post processing and Photoshop tips: Making a Material ID layer mask for post processing.

 

Here we have a simple bathroom scene that we will create a Material/Object ID layer mask for better control of our post processing.

 

The goal is to have a simple way of selecting particular materials or objects in photoshop(or your favorite photo-editing software) for individual settings such as contrast or exposure.

Particulars of importance will be denoted by ALL CAPS

 

Step 1) Setup your camera the way you like it and SAVE THE CAMERA(in plan view in the associated toolbar) . 

Step 2) SAVE YOUR PLAN, then we will resave the plan, giving it another name such as "Simple Bathroom Material ID Mask."

Step 3) In "Simple Bathroom Material ID Mask," Switch to vector view, then open technique settings(same drop down as where you found vector view) and set shadow intensity to 0% and make sure "Opaque Window Glass" is checked.

Step 4) Optional: Open your original plan and saved camera and start the raytrace process, if you have your system setup properly you should be able to raytrace and do the next steps simultaneously

Step 5) In your "Simple Bathroom Material ID Mask" plan, start painting the materials in your room as basic color blocks. When you are finished, the room should look like this:

Step 6) Export the current image IN ".PNG" FORMAT(jpeg is NOT lossless and you will get color artifacts in the export) then switch back to your original file's raytrace. Save the ray trace. You should now have two files, your raytrace, and the material ID image.

Step 6a) For the purpose of this tutorial I am going to perform a second ray trace using only exterior lighting to get an overexposure outside.

Step 7) Open your raytrace in a photo editing software that supports layers. For this tutorial I will be using Photoshop CC. Add your material mask as a separate layer and turn off the visibility of your mask layer. It should look like this:

Notice the layers in the bottom right. The Material ID mask is selected yet visibility is clicked "off." Also notice I have used the magic wand tool to select just my shower surround and the window. You should begin to piece together why this Material ID mask is so useful!!

I will now add my second render with my over exposed exterior behind my primary layer

Step 8) Select just the window and switch to the overexposed exterior. (There are many ways to do the following, this is just one method) With an active select tool right click on our window selection and invert the selection. This will select everything but the window. Now we delete everything but the overexposed window scene. Back in the layer settings, I can move the opacity slider of the layer to effectively blend my new window with the original raytrace.

Step 9) Tweak your raytrace, have fun with this, its a great tool for switching out colors or patters of materials while still maintaining proper lighting and shadows. 

This is a poor example as I didn't let the raytrace finish removing noise but look at what can be done with just a few quick clicks, perfect color changing or exposure/brightness/contrast tweaking in sections.

 

This may be a confusing tutorial, I will add anything reasonable to this tutorial to clarify steps or purpose,

Cheers,

 

[TheKitchenAbode]

Rene - Great tip/example of how beneficial and important some post processing work can be. Much faster than trying to make these adjustments using the rendering engine. Here is a link to a great Photoshop tutorial site that describes a wide range of techniques and how to do these types of things, the instructions are well laid out and fairly easy to grasp.

 

https://www.photoshoptutorials.ws/

 

Excellent point concerning the PNG vs JEPG export file format to avoid those nasty color artifacts.