ZBrushCentral

Troubleshooting importing obj files

ZBrush Usage Questions
#1

I don’t know how to better title this as it’s technically two questions, i’ve been moving some 3d scanned obj files into zbrush to play with and have a few issues.

  1. The imported files seem to really slow things down, is there something I am not aware of, or a way to make these imported files easy to work with? An example is a OBJ of a scanned sculpture, meshed in another software (revopoint’s revoscan) showing a final file size of 379mb. I am on a 2015 macbook pro, 2.5 GHz Quad-Core Intel Core i7. Sometimes I notice sluggish activity just doing regular sculpting with stock tools when i have used dynamesh and have it set above 400-500, or if my division count goes above 4. Could be that my laptop isn’t great for these tasks, but it should be able to handle these OBJ’s correct?

  2. When I import one of these scanned OBJ files, they are not on axis, usually tilted or not aligned to the view camera. I want to touch these up hopefully using symmetry activated, however the original sculptures that I scanned and am now working with were originally designed to be symmetrical but because they were done by hand the mirroring isn’t going to be perfect (these are masks i had made from polymer clay and sculpting tools). Is there a way to get these imported OBJ’s aligned correctly like stock subtools? Are there other zplugins or tricks available to make touching up and filling out these imported scans to make it easier for me to prep them for re-working and eventual 3d printing?

Here is a screen shot for reference, front and rear (don’t know why rear view shows up like that?)

Screen Shot 2022-06-24 at 3.29.50 PM
Screen Shot 2022-06-24 at 3.29.50 PM2880×1800 254 KB
Screen Shot 2022-06-24 at 3.32.34 PM
Screen Shot 2022-06-24 at 3.32.34 PM2880×1800 209 KB

#2

Hello @ndsugi,

I can only give you general answers here.

  1. Performance.

Recall that ZBrush is almost entirely CPU driven, which means that the CPU handles both modeling and navigational actions.

I couldn’t tell you anything specific here without examining the files. However there are several general factors that may be impacting performance. Performance in ZBrush will be affected by:

  • Number of points on screen being rendered, including all visible subtools.

  • Number of pixels on the canvas being rendered. The more zoomed-in a model is, the more space on the canvas being occupied, the more pixels need to be rendered. The higher the resolution of the canvas document, the more this will multiply that effect.

  • Certain features like Dynamic Subdivision can impact performance if applied to a high resolution model.

  • The form of your mesh. ZBrush is optimized to work with multi-resolution meshes. If a model has lower levels of subdivision available ZBrush will display these when navigating with or transforming the model, thereby keeping points off the screen and keeping performance high. If a model is freshly imported into the program at a single level of subdivision, then it won’t have any lower levels of subdivision to preview and the program must display all the points when navigating. This will be slower.

  1. Symmetry for scanned models.

Perfect mathematical symmetry is generally only possible for models that have been deliberately created in a digital 3d space. It is unlikely that you will be able to position your model in such a way that it results in reliable symmetry. In order to create this you would need to position your model as closely as possible to the center of an axis as possible, and then mirror the geometry from one side of the axis to the other.

This could be done with with the Tool> Geometry> Modify Topology> Mirror and Weld function, but keep in mind this feature only works in one direction. In some situations it may be necessary to first flip the geometry from one side to the other with Tool> Deformation> Mirror in order to get the intended side to mirror.

Good luck! :slightly_smiling_face: