When working with 3D scanned assets it’s desirable to have the true surface color without the effects of lighting. This filter approximates that original color.
UnLight.ffxml for FilterForge 4.
The filter takes the raw scanned color and the indirect illumination as image inputs.
|Raw color||Indirect illumination||Un-lit color|
The example above is a scan of a rock, baked onto an encompassing, low poly mesh. The first image is the raw color which includes captured ambient occlusion. The second image is the baked indirect illumination: the contribution of the environment to the final color of the surface. It is very important to get this right in the 3D scene by approximating the original light conditions as closely as possible.
In this case my job was rather easy: a single white hemisphere closely resembled the cloudy sky under which the object was captured. (By the way I used Autodesk’s Memento photogrammetry service.)
After feeding the filter those two images I tweaked the Gamma and Saturation boost parameters to my liking. The latter is for increasing saturation in occluded areas.
– If possible capture objects in even, diffuse lighting like on a foggy or cloudy day, because it’s easy to recreate those conditions in the 3D application. Smaller objects could be put inside of a white paper lantern, lit from above.
– When scanning the mesh also try to capture some of the immediate surroundings, especially if they have strong colors. In the following example the tree bark receives a considerable amount of green bounce light:
|High poly mesh||Low poly mesh||Low poly mesh un-lit|
The high polygon mesh contains the tree and a patch of grass around it. The green color contribution is easier to see on the unprocessed low poly mesh on the second image. The last picture shows how the colorization and the effect of the sky light were significantly reduced by the filter.
– Ideally the lighting environment is reconstructed from an HDR light probe captured along the mesh. However the filter has not been tested with such a setup, so there might be artifacts. If you run into issues please let me know.
– When an area is very dark due to occlusion then boosted saturation might produce weird colors since it doesn’t have much data to work with. In those cases manual retouching is required.read more
In the last couple of weeks I’ve been trying to develop a good asset authoring workflow for UnrealEngine 4. I looked at several possible solutions but none of them seemed good enough for my purpose: prohibitive cost and multiple asset transfer steps were the most common problems.
The trouble was that MODO’s standard surface material is not physically based so baking it’s properties won’t yield textures usable in Unreal. So I took a big breath, fired up the C++ SDK and made a custom material: it allows me to texture a model in a physically based manner with the preview viewport providing near realtime feedback. The look in MODO is quite close to the result in Unreal:
Most of the differences can be attributed to the different ways they handle the environment. (Extra highlights due to unclamped HDRI and less color contribution in MODO.)
The custom material is available for download on the UnrealShader for MODO page. It’s not feature complete and will see some more tweaking but should be already useful for creating opaque objects.
* Photoline is a great piece of software, I recommend it to anyone not happy with Photoshop.read more
I’ve finally had the time to write about the Punisher project I worked on.
Modo 401 was just released at that point and I jumped into a quick project to see how the new features and the bugfixes are working out in real life. I created a few objects, from concept art to the final in-game version. I took notes, swore a lot, and when the project ended, I started writing.
It was an interesting challenge to cover all the important features while not exceeding the word count limit. It took me a few rewrites but with the kind help of the editor the article eventually made it to the November issue. If you can get your hands on either a printed or a digital copy, it’s on page 34. :)read more
“Good news everyone!”
The latest build of the Unreal engine is publicly available, free for educational and non-commercial projects: Unreal Development Kit.read more
This article at Eurogamer does a great job at pointing out weaknesses in the concept of OnLive. I like the smell of the scientific method in the morning (well, midnight…).
The guy’s strongest argument I think is that if they indeed managed the necessary technological breakthroughs, why do they bother with video games? That video compression thingy alone would be worth a stellar amount of money for the military or any telecom company.
EDIT: Another article on the topic.read more