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Resetting Transform. Bug or...?

ZBrush Usage Questions ZBrush 2022 Usage Questions
#1

Hi. I’m really not sure if this is a bug or if there’s a proper way of fixing this inside ZBrush itself. The easiest thing to do is sort it out in Max or Maya and send the mesh straight back, but it’d be useful to know how to fix an issue like this in future.

I made a very simple caruncle for an eye socket in ZBrush using a Sphere. I did change the scale first under Export because every time I scaled it down so it was tiny, a DynaMesh resolution of 128 made it disappear. So I adjusted the scale to 0.01. Then, when I DynaMeshed it at a low resolution, it worked correctly. However, if I try to duplicate and mirror it for the other side, the position for the duplicate seems to reset back to where the Sphere came in, so it’s miles away from the rest of the model. Apart from taking the first part into Maya or Max and resetting the transform, what would be a way of correcting it in ZBrush?

Thanks

EDIT: Didn’t realise changing the Scale under Export applied to every other mesh, too. So I put it back to what my head was at - 7.5 - so the width of it was correct. However, the same problem still happened with the duplicated/mirrored caruncle. Resetting the transform in Max/Maya fixed it, but I’m still curious if there’s a way of fixing an issue like this within ZBrush. :slight_smile:

#2

Hi @DustyShinigami ,

There are several overlapping problems here:

  1. ZBrush works best with meshes with an XYZ world size of around 2. Meshes drastically larger or smaller than this may experience a number of issues in the program. If a mesh is properly imported into the program using the Tool> Import function while the default polymesh3d star is the active tool, it will be auto-scaled and centered to work in the program (does not apply to GoZ). The values required to restore the tool to its original size and offset are recorded in the Tool> Export menu. Those settings are saved on a per-tool basis and are unique to that tool.

  2. I don’t recommend changing the scale export factor. This information is saved on a per tool basis and contains the values required to restore the tool to the correct size on export. If you alter these values you will experience scale shifts between programs.

  3. In order to work correctly a mesh needs to be imported while there are zero values in the Tool Export menu. If there are non-zero values in that menu, for instance if another tool is selected, the incoming mesh will inherit those values even if they aren’t the correct values to restore the incoming mesh to the original size. So you only want to do this when importing a different version of the same mesh, for instance to update UVs. Otherwise this may result in scale shifts when working between programs.

  4. It is recommended to switch to the default polymesh 3D star primitive in the Tool menu before importing any mesh. This is only because that tool has zero values in Tool> Export, and you will be ensured of a clean slate and the proper values. If any other tool is active when you import, the import will inherit those values incorrectly and lead to scale shifts when working between programs.

Re: Dynamesh.

Meshes that are too small in the worldspace may experience a number of issues. Dynamesh may be unable to capture the form accurately even at high resolution settings.

Try clicking on the dot button on the right end of the Dynamesh Resolution slider. This will activate an alternate mode designed to capture small mesh detail by introducing resolution multipliers when the mesh falls below certain size thresholds. You may experience better results with one mode over the other.

Good luck!

#3

Thanks for the reply. Yeah, I tend to make use of the dot if I don’t find the resolution is strong enough.

Regarding not changing the scale export, this was something I learned about through a course. It involves getting the correct measurements of a human head and working from a Sphere primitive and then DynaMeshed. One of the measurements was the width of the head, such as this:

Acrobat_BrDOqebYFp

The measurement is found out using the Transpose Line. But in order for it to fall around the 30-50th Percentile, which is 13-15cm, the export scale needs to be set to 7.5? If the mesh itself is scaled up, it can make the DynaMesh too much, even at a lower resolution?

What would be the recommended solution to get the right scale and measurements in this case? Is it recommended to be done in Maya/3ds Max first?

#4

The Tool> Export Scale function is designed to restore the mesh to the original size after import. If you alter this value you will experience scale shifting when working between applications which may cause problems if rendering at a certain scale in the other program. This is designed to work seamlessly without user input, and it is not intended that the user have to manipulate this value in most scenarios.

If you want to alter the size of a mesh, use Tool> Geometry> Size.

Size units are relative. Make sure your model is proportionally correct, and it will be correct when you scale it to output at any given unit of measure. So create your mesh to whatever scale you want, import it into ZBrush using the correct procedure and do not alter the Tool> Export settings. It will import into ZBrush at a size necessary to work well in the program, and it will export back out at the original size as long as you haven’t changed anything in that menu.

Re: Dynamesh.

With the exception of meshes that are especially tiny, mesh size does not contribute to the amount of polygons delivered to a Dynameshed mesh. This is determined by surface area and the Dynamesh resolution slider. For most meshes this will max out around 3-4 polygons and this will not change not matter how large you make the mesh. Only increasing the amount of surface area that the mesh occupies within its bounding box will alter this.

:slight_smile: