Hard Surface Modeling

[chippwalters]

Hey Guys,

Just purchased 3D Coat because of the stupendous Ticker animation on the front page for hard surface modeling. Great stuff! But, I'm pretty new to all of this. Below are a couple renders in Thea Render of crude test OBJ models created and then exported from 3D Coat using the new Tinker Toys pack. Very sweet pack and a wonderful contribution by Tinker to this community. Much thanks!

I have a few real problems understanding how to move out from 3D Coat to other apps when using hard surface models. I've tried going the auto-retopology route with limited success. For instance, in the pictures below, I have created a single voxel volume which takes up about 1/3 of the grid, and is [2X] resolution (if I use single resolution, there appears to be too much artifacting). When I try to auto-retopologize the model, it mostly hangs on my dual quad 6GB system. I've turned off "try to create edge loops' and when I finally get the object retopped, using the default settings, it looks really, REALLY BAD. So, I've been exporting as triangle mesh (OBJ) with a reduction percent of 95% (taking it down to under 1 million polys) and I get the images below. Still, as you can plainly see, there is a bit of artifacting.

What I want to ask are the following questions:

• Is there any secret to using auto-retopology on large meshes for hard surface models?
  
• Is there a way I can reimport this triangulated OBJ but attach to it a normal map created from the original voxel volume?
  
• Are there any other suggestions on how to maintain the crispness of the hard model?
  

[Rich_Art]

I can't help because I just ordered 3Dcoat myself but I want to say that the "doodle" looks nice.

Peace,

Rich_Art.

[Grandmaster B]

Yeah, looks cool! I can barely see artifacts. I guess such a scene is almost impossible (or simply takes too long) to (auto-)retopo unless you work with seperate voxel spaces , which may also retain harder edges. You may try Blender or Meshlab to reduce the polycount in a more generic way on the exported mesh. You can then import this back into the Retopo room of 3D-Coat and bake a normal-map for it.

[AbnRanger]

That's just too complex of a piece to expect near perfect results from the Auto-Retopo tools. Split the model up into logical parts, and try a combination of auto-retopo with guides, and manual retopo of areas that are just too problematic for the auto-retopo process. It can shave a lot of time out of the process, but not THAT much.

[Psmith]

Yes, by all means divide your model into voxel layers, increase resolution on those layers which need it most and try the following techniques for better AUTOPO results:

1) Since spherical objects create the biggest difficulties for AUTOPO, "slice" these objects laterally with "guide" strokes, like you are cutting a tomato.

2) Be sure to paint density on these same spherical objects to assure proper recognition of details.

3) Use the same "slice" technique near hard surface edges, (on both sides of edge), for objects that are more rectilinear.

4) Don't try to draw guides around circular details and holes that go all the way through - AUTOPO is good at circling these formations with loops.

5) On radially shaped objects, (like gears), "slice" through the object going from the space between teeth, through the center, to the opposite tooth recess, doing this between every gear tooth.

Greg Smith

[chippwalters]

Wow. Very helpful. Thanks a bunch everyone. Greg, am I correct you want to place retopology 'slices' in the same place you would 'slice' a hard surface quad model in order to create sharper edges?

Here's another render and in it you can see the extreme artifacting. Thanks again!

[chippwalters]

One other question.

Would it be recommended to create the large parts of this model as one voxel volume (as above) and retopo it (which shouldn't be too hard as there's much less detail), then finish 'detailing' in Paint using displacement tools?

[Psmith]

Mr. Walters:

Here is a graphical example of slicing for AUTOPO. I left the Wizard default settings as is.

Regarding adding hard surface detail in the Paint Room, try using high resolution "Alpha" or "Pen" stamps for adding greeble details. Assuming you have subdivided the automatic topology sufficiently in the Retopo Room, you should get good results, (only you can be the judge).

Also, some of the artifacts visible in your example could be eliminated by increasing resolution of the voxel model as far as your machine can tolerate, (which will result in longer AUTOPO rendering times) - but the results might be worth the wait.

Greg Smith

[chippwalters]

Here is a graphical example of slicing for AUTOPO. I left the Wizard default settings as is.

Greg, thanks much for that. So it appears the topo lines are pretty much in the same area as one would create quads in. Great. I'll play around with it all this weekend. :-)

[Monsoon]

Heya Chipp!! Good to see ya here! You're gonna have loads of fun with this handy dandy versatile tool!

[chippwalters]

Heya Chipp!! Good to see ya here! You're gonna have loads of fun with this handy dandy versatile tool!

Hey Mark! I've been testing this out with Thea Render as well. They seem to be a decent match. There's so much to learn in both programs!

Are you an accomplished user of 3D-Coat? I think there's really something to this hard modeling stuff, but I just can't quite get from the voxels to the topo yet. My goal, as you probably know, is to create Speed Renders where I can model and render in one sitting. I'm not really after the week long modeling, UV mapping, Texturing ordeal, then pop into a scene and take another week to compose and render.

I think 3D-Coat may be able to handle some really awesome Greeble/Nurnie hi-tech objects of all sorts and sizes. Once I get going, I'll create a page..

[Psmith]

Time is definitely our enemy. I would hate to admit how many, (countless), hours I've spent on what I thought were simple projects, like your speed modeling/rendering in one session. It really should be easy and fast to do these things, not requiring you to shift brains too many times in the process.

My hope is that 3D-Coat will become that app that lets us lay down our thoughts just like sketching them - only in Technicolor 3D.

I think Andrew gets it.

Greg Smith

[Steve C]

I hope you folks do not mind me chiming in.

Good looking model btw.

I am wondering how you get those nice sharp edge details?

I have tried and I get a lot of jagged edges even using the default shapes.

If you know of a tutorial that I may have missed let me know.

Thanks.

[Psmith]

Steve:

If you are making a hard edged model starting with Primitives or with supplied Greebles, scale the starting shape up substantially. In 3D-Coat, when you scale something in relation to the grid, for example, you are actually increasing its resolution.

So, if you start with a scaled, (high resolution), base shape - everything you Merge will also be in proportion, (after you scale these, as well), to that initial base shape and its corresponding resolution.

Try this out with some simple Primitives and see if those jaggies disappear. If they don't, you can still apply "Inc. Res" in the Voxel Tool panel to bump up the resolution. But, it's better if you use the initial Primitive or Greeble scale handle, (the center one), to establish resolution and assure very crisp edges.

Greg Smith

[michalis]

Would it be recommended to create the large parts of this model as one voxel volume (as above) and retopo it (which shouldn't be too hard as there's much less detail),

What I'm seeing here is some boolean operations on the base model and attachment of lot of detailed objects in or on it.

So after the retpopo of this base, export it and ... adopt all the obj merged details directly from the file they are. These are obj with some fine topology already and I really can't understand why you have to turn them to voxels and retopo them. I really don't understand this in most cases.

So do the sketch here and finish it somewhere else.

[Psmith]

It does make sense to keep things as polygonal objects if they start out that way. The exception would be when you want to perform boolean operations, for which voxels are the ideal medium.

Just another example that makes a case for 3D-Coat having a dedicated set of tools for working with polygonal objects. Saves a lot of "translation" back and forth.

If, however, Andrew's Automatic Topology Creation Algorithm, (AATCA), ever becomes super-intelligent, then there will be good reason for merging objects into voxel space.

Greg Smith

[Steve C]

Psmith:

Thanks for the insight.

I have had 3d-coat for a while.

I do not get as much time to work with it as I work for a company that has me doing technical documents rather than what I enjoy. I hope to change that soon.