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Silentman

What is the purpose of Retopology, the BIG why ?

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Hey all, i hate to ask what maybe a really dumb question, but i'm new to sculpting in 3D and i'm wondering why i would use Retopology, what purpose does it have? is it so i can texture my models, are they not texturable without Retopology, or does it have more to do with Import and Export, anyhow, i am somewhat lost on the matter and would really appreciate an explanation on it's purpose and uses.

Thanks in advance.

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Hey all, i hate to ask what maybe a really dumb question, but i'm new to sculpting in 3D and i'm wondering why i would use Retopology, what purpose does it have? is it so i can texture my models, are they not texturable without Retopology, or does it have more to do with Import and Export, anyhow, i am somewhat lost on the matter and would really appreciate an explanation on it's purpose and uses.

There are lots of ways you might use the retopolgy tools, but the main way they are used today is to free you from thinking about polygons until you have to. It used to be that if you wanted to create a model, you would have to start in something like Maya, LightWave, etc, and build everything up polygon by polygon, until you had a workable mesh. Then you would paint it, so it looked "real" and render it in an animation app.

The problem was that to be a good polygon artist, you need to be part scientist -- which ran counter to the way a lot of artists think. Applications such as zBrush and Mudbox allowed artists to get involved in the creation process, because it was more like working with clay and traditional artist mediums, but the problem was the result was millions of polygons that would choke any animation program.

Retopology tools came to the rescue. By laying down a low-polygon mesh over top of the high density model, artists now had the best of both worlds. They could model in a more natural and organic way, and then lay a mesh over top of it that had a MUCH lower polygon count.

To answer your question though, there are three times I can see using retopology, even for a casual artist:

1. Create clothes for a model. You can lay a mesh out on your model, and have it "cling" to the form, and use this as a starting point for shirts, coats, and what have you

2. Create a better arranged mesh to sculpt on ("normal" sculpting, not voxel sculpting) One of the real probelms with sculpting on polygons is if they do not flow the right way, you have to add a lot of them to get the edge you want. The classic case of this is if you have ever watched a head sculpting tutorial that starts with a sphere. (zBrush has a ton of these on their site.) It works OK, until you get to the moth. And then the line of the lips goes counter to the edge of the polygons in the sphere -- even when you subdivide many, many times. This is, honestly, why so many zBrush models have a gajillion ploygons. The casual zBrush user has never taken the time to learn polygon flow, so their solution is to crank up the sub-divisions until the polygons are small enough that it is possible to get the edge they want. Trouble is that subdividing a mesh increses the polygon count exponentially (by a factor of four, in fact). So this approach creates VERY dense meshes. A better approach would be to retopolize your mesh before scultping so the edge flow of your polygons worked with you instead of against you. Again, this does NOT apply to voxel sculpting which has a different underlying structure for the sculpt.

3. Lower the density of your mesh so you can animate it. If you plan on exporting your model into any animation application -- even if you just want to pose it and render it there -- the polygon count becomes an issue. XSI is very friendly to high density meshes, but other apps will absolutely choke if you try to import a couple of high res models.

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Thanks alot, MarkG, after reading that i now have a very good understanding, and can also see why sculpting lips (poly style) was not going too well for me. I really appreciate the time you took to explain it to me.

Thanks very much :)

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Thanks alot, MarkG, after reading that i now have a very good understanding, and can also see why sculpting lips (poly style) was not going too well for me. I really appreciate the time you took to explain it to me.

Thanks very much :)

Yeah, a really easy to read & understand reply Mark. :clapping:

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hey just to add another use.

4. I use retopo tools in 3D coat to make a complete low poly model of my high poly model for use in a video game. It doesnt matter wether the model is poly sculpted or voxel sculpted it is always far too high density in polys to actually use in a game engine like unreal or marmoset. So retopo comes to the rescue and also allows me to have fewer polys to worry about which makes uv mapping for textures easier. I can take a model with 12million polys and turn it into a game quality model with 8500 polys and still have it look just as good by baking textures(normal, AO) from the high poly mesh.

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Ghostdog and Silentman... thanks! You go off on a big post like that, and sometimes you wonder whether people think you're some blowhard. I appreciate knowing it helped...

GED: Yeah, games... another good reason. It sort of follows under #3, lowering the density of the mesh... but you add a very good point about baking. Being able to bring the detail from the high density mesh into the lower polygon version has really revolutionized things, for sure!

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hey just to add another use.

4. I use retopo tools in 3D coat to make a complete low poly model of my high poly model for use in a video game. It doesnt matter wether the model is poly sculpted or voxel sculpted it is always far too high density in polys to actually use in a game engine like unreal or marmoset. So retopo comes to the rescue and also allows me to have fewer polys to worry about which makes uv mapping for textures easier. I can take a model with 12million polys and turn it into a game quality model with 8500 polys and still have it look just as good by baking textures(normal, AO) from the high poly mesh.

GED, what's your methodology for baking?

I've recently become interested in trying to bake down from a hi-res model to a lower one but I'm not sure where to start.

I've been looking at XNormal but I haven't taken the time to try and learn it yet.

-Will

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Hey all, i hate to ask what maybe a really dumb question, but i'm new to sculpting in 3D and i'm wondering why i would use Retopology, what purpose does it have? is it so i can texture my models, are they not texturable without Retopology, or does it have more to do with Import and Export, anyhow, i am somewhat lost on the matter and would really appreciate an explanation on it's purpose and uses.

Thanks in advance.

I found a use that I would never have anticipated. I had a 3DC project with very high res (I discovered later that it was consuming 7.75 gbs of RAM) and decided to refer to a C4D file of the same object when Vista gagged. After a wait, I closed C4D in Taskmanager. When I got my RAM back, I opened the same file to discover that all objects had been made 'editable' (that is, 'polygonal') and the materials reduced to the default gray state.

So I had the problem of HN resolutions on my formerly low res objects. Solution: Retopology! Beware! This process is hypnotic and when you resurface, you may find that more time has passed than you were aware of. Anyway, I am making a much nicer mesh that wont require anymore smoothing than that provided by Phong. :clapping:

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I have the same question. I'm not yet familiar with 3DC, I'm trying to pick a 3d sculpt application. I understand the purpose of retopology. But if I'm in a hurry and trying to model a rock or a large boulder, a polygon reduction program/plugin would be enough + normal maps on top.

Is this a mandatory step in 3DC ? For example with Mudbox - I can just import a model, quickly paint/sculpt some details and export back. Or you could just export the maps/normal maps. No retopology necessary.

Maybe it's not mandatory in 3DC. I'm just asking because everywhere you read about 3DC, this retopology step is also discussed. While in Mudbox you don't hear about this.

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Retopology is appropriate when you have created a model in voxels. Import your model (with a UV map of it's own) and Paint 3D detail and export your maps. You need not export the model as you have one in it's native format (not OBJ for 3DC). But the painting you did is on those maps.

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Thanks.

1. Can I also sculpt details on the model I just imported ? (without retopologizing).

2. And can I also export the model with the new details in a common format like OBJ ? In case I wanna make the normal maps in another program.

3. If I create a model in voxels - can I export that as a polygon model - without the retopology step ?

4. Or can I export normal maps and then apply a simple polygon reduction before exporting the model ? Right inside the 3DC ?

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Another use for Retopo in 3DC is making clothing and armor and such for characters. First make a retopo mesh on your character in the shape you like and add a little Additional Extrusion, then in the voxel room pick the Cloth tool and "Pick From Retopo", subdivide it, and hit Enter. Bam! you have your cloth. This is how I've been making all of the accessories for my current character.

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Sorry that response wasn't just to you, it was for the whole thread.

1. yes sure retopo is something you can do after sculpting if you like.

2. Sure, go to File > Export

3. Already answered in 2.

4. In order to put normal maps on it you will want to retopo, because you need the retopo mesh to paint on, that's where your UV map gets applied. If you just want to export and reduce polys that's all done in step 2. above.

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Thanks again and I think I found the answer to question 4 in a youtube tutorial.

If you don't wanna perform manual retopology - you can just do an automatic one with Quadrangulation. It is probably good enough for rocks and other less precise objects.

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Thanks again and I think I found the answer to question 4 in a youtube tutorial.

If you don't wanna perform manual retopology - you can just do an automatic one with Quadrangulation. It is probably good enough for rocks and other less precise objects.

Auto-retopo is the best solution for anything not requiring perfect edge loop topology (even though you can get really close with very little work). You would probably still want to paint some strokes so you can control the UV seam though (ie, a line on the bottom of the rock)

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You can also take someone elses model, do a retopology and then claim it as your own. Maybe even sell it.

I haven't seen much discussion on hijacking other peoples work. Is it a concern in the industry?

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Well you don't even need retopo for that. If people want to steal work they will just do it. I think it's a concern, but not a huge one since most people know it's a very small industry and when get caught doing something like that it's not long before everyone knows about it.

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GED, what's your methodology for baking?

I've recently become interested in trying to bake down from a hi-res model to a lower one but I'm not sure where to start.

I've been looking at XNormal but I haven't taken the time to try and learn it yet.

-Will

sorry I forgot I wrote in this thread, yes xnormal is really good, give it a try and if youre still confused look up some tutorials, there are 2 things to consider when baking 1. your uv map is nice and flat and none of the uv islands are overlapping 2. your objects scale is compatible with xnormal. If things come out wierd I always check my scale settings first.

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...because everywhere you read about 3DC, this retopology step is also discussed. While in Mudbox you don't hear about this.

One reason for that might be that you can't do retopo in Mudbox...;)

Retopo might also be discussed a lot because many people, myself included, use 3DC solely for retopo. Those retopo tools in 3DC are simply put awesome - especially now with auto- retopo.

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I'm new to 3-D Coat. A novice at 3-D modeling. Have worked in Poser, Carrara, some 3d Max and Lightwave. I'm primarily an artist who wants to use the tools. 3-D Coat is fantastic and I've already carved out a nice model. I'd like to put some bones in it. Then I'd like to pose it in Poser or Daz 3-D.

So, I should use retopology to bake the figure first or just export as an OBJ? i suppose what I;m asking is if retopology is a must and in what situations.

Your responses are appreciated.

jt

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The object you created in the Voxel room needs a mesh applied to use in another app. You can do this with "Auto Retopo", which is very generous with the quad count, or do it yourself for fewer quads if animation is your goal. The native voxel mesh is a dense mesh of tris and would be troublesome in an OBJ file.

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This is just a little helpful information to go with Tony's

What I like about voxels compared to the old days, is that I can create my voxel model then use that as the base to build my polygon mesh on top of it.

We really have not gotten away from usable polygon modeling but voxels have reverse the order of the pipeline. Polygon modeling was not my favorite but was necessary if I wanted to paint my own models and render them.

Now with voxels modeling has become much easier and enjoyable task as 3DCoat's retopo tools are great...

You can use the auto-retopo feature and auto-uvs if you are looking at just rendering your model or posing them using bones.

For animation it's best to manually create your own retopo mesh and uv map for textures,normal maps etc...

This is a model I'm finishing up for using in Messiah Studio.

Manual retopo and uv map.

post-518-0-01160500-1298921179_thumb.jpg

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Thanks for these responses. To be clear:

1. Sculpt something with voxels

2. Use Retopo to scale down the number of polys (and get the polys right)

3. Save the resulting retopo model as an OBJ for further use.

The voxel scuplted model can be used later to add clothes or other accouterments.

Is this close. Again, your assistance is much appreciated.

jt

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