X-13 RTRT Information
(Items that are specific and searchable terms in CA have CAPITALIZED letters)
Better understanding of a modern rendering engine may help alleviate some issues. If you are feeling overwhelmed by this info you can always uncheck the option for the RTRT in your RENDERING TECHNIQUES TOOL. Feel free to contact me for support or advanced training.
• In RTRT a low SAMPLE RATE is used in live CAMERA views.
• For exported presentations images similar to a CPU-based RT, set your MAXIMUM EXPORT SAMPLES as low as needed to eliminate fireflies and light leaks. The higher the SAMPLE RATE in RTRT RENDERING TECHNIQUES, the better the image(up to a point where benefits are negligible). This only applies to the EXPORT IMAGE TOOL. The higher the SAMPLE RATE the longer the processing time
• A SAMPLE RATE in basic terms is the number of samples from a camera of a given Objects Material ID as it applies to the geometry of an object, including colors, lighting, shadows etc. The more times something is sampled the less aliasing there exists in a final image.
• The more light exists in the scene the easier it is to Sample.
• You must supply ample light in adjacent rooms for the RTRT engine to properly process and "trace" your scene. Devoid of light, your exterior will be overly exposed, your interior may be underexposed, and you may have fireflies or light leaks.
• Ensure that your active Light Set is on and illuminating your scene, which is accessed a number of ways, one being the EDIT ACTIVE VIEW TOOL, in the CAMERA PANEL, under the LIGHTING SECTION. Ensure the lights that you want turned on are on and if necessary to troubleshoot, turn the color channel to a color so as to locate the focus of light.
•There is a built in denoiser when using the EXPORT IMAGE TOOL. So fireflies may be removed with the denoiser. If after the export there are still fireflies/noise, then up your SAMPLE RATE.
• With ample lights, an interior scene Rendering Technique Options might have an exposure from .15-.35, a Maximum Sample Rate of 500-1500, a Brightness between -10 to 0, a Backdrop intensity between 100-1000. This is not and never will be a universal setting, each scene needs adjustment according to the amount of light available to that scene.
• If your scene is underexposed you may need to adjust your lighting including the lumens of your light fixtures.
• SUN INTENSITY settings will do very little to help overexposure, underexposure, light leaks or any other trace related problems. This is the nature of a tracing engine. I do however recommend rotating the SUN so as not to illuminate your BACKDROP in an undesirable way.
• Live view will always be of lesser quality than an exported image using the EXPORT TOOL(because of the option to change the SAMPLE RATE, LIVE CAP Settings and the built in undisclosed denoiser.)
• Typical problem causing issues:
Caustics, Lights near transparent or translucent surfaces, lights of high Lumen values in one room juxtapose to lights of low lumens in an adjacent room. High resolution bump/roughness/normals maps in materials. These issues all cause difficult scenarios for attenuation and aliasing.
Some of the fixtures being used are not optimized for this new engine. Consider changing the material properties of any glass that is in close proximity to a light source.
There is a lot more to this, you can have some success with this info, but barely scratches the surface. For some incredibly good generalized rendering info, read the Thea Render Manual(free online) It has some fantastic info in it that applies to all rendering engines. The following image is from Chiefs RTRT
Bathroom shown is designed by Steve Price of the Beautiful Space Co. https://beautifulspaceco.com/
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