retopologing a zbrush object

NAIMA

Hi what's the best to make a low poly version of a high poly model in zbrush?
I have tried decimation master , reduced the mesh polygons from 4 milions to 700 k then imported in topogun beta demo and I see I lost a lot of the details , so I was trying the inzbrush tools for retopologizing and when I try to create ther zsphere and attach to the mesh it says please select a mesh with less than 15000 points or less poligons , but what thatmeans? What's the point of chosing a smaller developed mesh if my point IS tomake a smaller mesh?

cryrid

How much detail are you losing in the decimated version? You can either try playing with the quality, or possibly leave it as it is. You don't need all the detail when you're retopologizing (it'll just slow things down), you just enough to create the form / silhouette. Usually working on a medium subdivision level is enough for this.

NAIMA

but ok I can make the shape onthe version without details but then how do I take the details on the normal?

cryrid

If you're finished with the sculpt and ready to bake the detail onto the final retopo'd mesh, progams like xnormal can handle the transfer. Just export the highest subdivision level or use the decimated version (if you find settings that work well for you) for the high-res target.

If you want to continue sculpting on the retopologized mesh in zbrush, append it as a subtool to the original sculpt, subdivide it enough to get the polygons necessary for the detail, and use the projection tools to transfer the details from the original sculpt to the new mesh. It might help to save a morph target on the new mesh before doing the projection in order to be able to fix any issues in tricky areas.

NAIMA

the problem is that the highest sub level is over 10 kk polys and it says zbrush cant exports crashes and saves a save ....

cryrid

That's something to maybe contact Pixologic about, or look into your hardware. You should be able to export objects that have millions of points (it may result in OBJs that are >1GB, but still). Perhaps disable any polypaint and polygroups to see if it helps the export process.

ceebee

If 700k tris isn't enough to retopo you must be doing something wrong. You do not need details to retopo, just the basic structure and silhouette. Also FYI you cannot save out retopologized meshes in the Topogun beta demo just as a warning.

Once you retopologize your mesh to a low resolution one (say like 12k triangles or something) then from there you export your 10 "kk" (I'm assuming 10 mil, wtf?) model from ZBrush.

I'm assuming English isn't your native language because reading your posts gives me a headache.

NAIMA

No is not my language , but I coul dwrite much better , it is only that I was in a hurry and typed fast....

Anyway my original model is ( only for the top tool unmerged) 10 millions polygons , probably the count for the whole object is higher ... I have problems of crashing and freezing of Zbrush when I try to export or merge objects ....

DrunkShaman

Have you tried editing existing topology by exporting the low poly mesh and than exporting it to the program, than decimating the high and exporting that? Use layers.

According to the reviews, Zbrush Topology tool sucks.

Should you attempt this method that I suggested, save a duplicate file before following it through.

Oh and, you can decimate parts of the objects and delete the hidden geometry from the mesh. Like, you can make polygroups, split them out, and than decimate them one by one. keep that in mind while you decimate them.

EDIT: Do not merge them all at once.

EDIT2: In zbrush if you are are editing the geometry of the existing mesh using topology tool, the existing topology has to be under 15000.

ralusek

I'm not sure I fully understand your problem, but your workflow should look like this.

Step one, decimate your model. As everyone has said, 700k is going to be much more than you could possibly need for this, you could probably decimate to something closer to 50k, but as long as you have your sillhouette it doesn't matter.

Take the decimated obj into topogun or whatever you prefer to retopo in. At this point you go over it, and export the retopoed mesh. Depending on what you do, this will probably be around 10k, maybe higher or lower if you're doing low poly or film respectively.

At this point you can go to zbrush, go to your original non decimated mesh with all of the detail, append your retpoed mesh. I would subdivide it once or twice, project all to make sure it's conforming well. I find that projecting earlier on once or twice gives less errors. Then subdivide to a level you're comfortable with to capture all the detail, and project all again. Then go to your lowest subdivision level and export a normal map.

If you prefer to try xnormal instead, import your retopoed mesh and your 10k polygons and just project that way. 10k might be a little high for xnormal though, so i personally recommend zbrush.

if you're having problems with memory, remember that zbrush can use high definition sculpts for exporting normal maps now (this can allow up to 1 billion polygons). if you're going that route, i would subdivide to about 2-4 million, then switch to high def sculpting. at this point, you're only going to be able to sculpt on certain areas of the model at a time, so use the zproject brush to get the details from your original sculpt instead of project all. when you're done doing this for the whole mesh, you can export the normal map and it will automatically get a tangent space from your high definition sculpt.

hope that helped