Hi, it happened to me a lot mostly in heavy subtools. When there is so much subtool and export/import for the topology from other softwares (Maya) %90 of the time scale changes. In the beginning of the project I set my measurements to work better. I import the subtools in to Maya and it looks correct then edit it to import back to zbrush. Nothing looks wrong first. But when I try to export them from zbrush the scale changes. And then I check my zbrush scale. It also changes! So sometimes this is not happening. But most of the time my setted scale changes in zbrush file. Is this a bug or am I doing something wrong?
Hi @caliskanuzay ,
Most scale shift issues are due to improper import procedure. If you ever believe you are experiencing a bug, please contact ZBrush Support.
The effective world space in ZBrush is finite. Meshes that are especially over or undersized in that space will experience issues. When imported with the import function, ZBrush both scales the mesh to an optimal size (XYZ of 2) and centers the mesh in the worldspace. Meshes may be difficult or impossible to work with otherwise. So if you import two different versions of the same mesh that have different scales and offset outside of ZBrush, they will both be centered and look the mostly the same size in ZBrush.
The program records the values necessary to restore the mesh to its original scale and position in the Tool> Export menu. This happens automatically without requiring any effort for the user. This means that every mesh that has been imported this way carries around unique settings in that menu meant for that mesh and no other.
When a mesh is imported while another Tool is selected it will inherit those settings. This allows the mesh to be replaced in certain scenarios, and allows other meshes designed to fit the scale of the target mesh to be appended to it and keep the correct size relationship.
Where problems arise is if you import a mesh with another tool active at the time of export, and it inherits settings not meant for that mesh. Once that happens the mesh will be exporting at scale and offset settings meant to return the original mesh to a specific size and position, not the settings that would be required for the newly imported mesh. However, since the mesh will be scaled and centered to work in ZBrush, this scale shift may not be apparent until the mesh is exported. Now you have a file that is different outside of ZBrush, but may continue to look the same when inside of ZBrush because of the autoscaling.
Unless specifically trying to replace a mesh with a different version of the exact same mesh, the Tool> Export menu should have zero values in it at the time of Import. If another tool is selected it may have non-zero values active which will be passed on to the incoming mesh. It is recommended to select the default polymesh 3D Star as an import target before importing any mesh. This mesh has zero values in that menu, and you can be assured of a clean slate.
The procedure is therefore:
-
Select the polymesh3d star from the Tool menu.
-
Import the mesh with the Import function.
-
Repeat this for any mesh designed to fit to the scale of that mesh, and then append the subsequent meshes to the first mesh. Do not attempt to import those meshes directly into the target tool while it is active. If you do that the mesh will replace the active mesh but inherit its settings, causing a scale shift when exported.
-
Export the mesh. The mesh will export at its original scale unless you deliberately changed it in ZBrush. Sculpting may also change the size of the mesh, but those changes will be proportional to the original scale.
Note that the above only applies to importing meshes manually with the Import function. It does not apply to GoZ.
I understand and yes this can be a solution but sometimes it is very waste of time to do that. Direct import is way better and I think maxon can fix it with the other updates.