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Be careful because the model unit found may look slightly different from what is rendered if a scale is also set inside of the A3DTopoContextData. |
Why does values do not correspond to my part unit?
Because the HOOPS Exchange API is storing all values (for both brep and tessellation) in mm.
So in order to retrieve the value expressed in the corresponding part unit, it is required to apply all the scales that are present in the whole transformation chain (see A3DAsmProductOccurrenceData::m_pLocation).
Why my unit is different after an export to another format ?
It all depends of the format used, different cases are possible:
Some may just do not support the concept of units at all (especially tessellated ones, like OBJ or STL).
Others might be using some session variable (meaning that values are in fact converted on the fly depending on the selected unit). So nothing is actually stored inside of the CAD file.
Finally remaining ones could just use a specific unit set as default.
So here’s a non exhaustive list of which unit are used by default for most common formats:
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How can I overwrite units inside of a PRC file ?
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