Requesting Critique | Popcorn Machine Prop
This popcorn machine is a prop I created to work on my hard surface modeling skills as part of my journey to become a better prop artist.
Tools Used:
- Modeling: Maya
- Texturing: Substance Painter, Photoshop
- Rendering: Marmoset Toolbag 4
One unique aspect of this project was the popcorn itself. I 3D scanned real popcorn and baked it down onto the pile using a diffuse height map. While this was an interesting experiment, I’m not entirely happy with how the top layer turned out and would love feedback on how to improve it.
I’m looking for overall critiques, including topology, texturing, and lighting. I plan to wrap up this project within the next week or two, so any feedback to help polish it further would be greatly appreciated!
Here are the renders and wireframes along with the original reference:
Thanks for your time and insights!
Replies
My biggest critique would be the pile of popcorn, looks very flat and angular, the poorer quality of the model and texture sticks out compared to everything else.
There are some small parts on the model which have a lot of extra detail which could be optimized. Which would give you more room to improve the popcorn pile. The metal hose, the switches at top front, the dial at bottom front, etc.
The wireframe shots look like they don't match the non-wireframes. Popcorn pieces missing, etc.
One trick for the popcorn could be to add a detailed silhouette along the edge of the glass. Probably best as actual geometry, but the rest of the mound could remain fairly flat.
It would help to see your AOVs (arbitrary output variables, also called Render Passes): albedo/diffuse, roughness, normal map, etc.
Could you elaborate on that, please? Might be about terminology, but I don't quite follow. You scanned individual pieces or a bunch of popcorn? And since you seem to be using a displacement map / tesselation, did you take the height map from the actual scanned data or from the diffuse? The pattern doesn't seem to align with the diffuse, though.
The "top layer" should cover everything that's visible, not just the literal top. Are the single popcorn pieces separate elements or part of the displacement, too?
Right now, the machine would sort of work as a background prop that we don't get too close to, but like Eric pointed out, there is some unnecessary detail that could be spent elsewhere in that case, the tiny screws being another example that would work well as being textured only.
If this is a hero prop, then the popcorn is sort of the hero of the hero prop. Displacement could be justified, but collapsing that down to a reduced mesh might be the "cheapest" solution (but don't take my word for it and the additional step makes more sense for a one-off object).
In any case, the scale of the displacement for the large chunk of popcorn seems off. The smaller surface detail can be covered by the normal map, while you want the shapes of the individual pieces represented by the displacement (or geometry).
For the best result, you could cover all visible sides of the heap with indiviual popcorn pieces and have a smaller, solid block in the center.
For a displacement solution, you'll also want the block which is to be displaced to be smaller, so you have some space for it to be displaced into (or you do negative displacement only). Any part where we see the silhouette being especially important.
Parallax occlusion for the flat areas and single pieces along the edges might work, too, but is probably overthinking it.
As for the textures, you have the choice between making a tiling popcorn texture or a unique one. For a one-off piece, it might be quickest to simulate the heap and bake that down, including taking the heightmap from that (which sort of sounds like what you intended/did, but the outcome looks nothing like it). I can't quite make out if the high contrast in the popcorn is due to the diffuse/albedo or perhaps lighting, but the former should be more even. The texture is blown out by the lighting, too. Maybe there is a tiling mismatch between diffuse and height map? If you ever need the heap to be represented by flat surfaces, baked shadows / AO will be important to at least get some semblance of depth.
Lastly, you'll want some sort of sub surface scattering or suitable fake for the popcorn. Black shadows will probably look odd/dirty.