Dear Bashant,
After looking at your data I have come up with the following pipeline that would export each grain and an STL file.
The pipeline imports a single CTF file (#1), performs the proper sample reference frame rotation (#2) and then starts the processing.
#3: Multi-Threshold Objects: Create a Mask that labels each voxel as either a valid (good) or invalid (bad) scan point. We use the ‘Error’ value to accomplish this.
#4: Convert Orientation Representation: We convert the Euler Angles to Quaternions for later use
#5: Segment Features (Misorientation): We now segment out the features (grains) using 5 degrees misorientation.
#6: Fill Bad Data: We use this filter to fill in the “bad” scan points that the OEM software could not index by using surrounding voxels.
#7: Compute IPF Colors: Create the IPF Coloring for the voxels. This is not required but helps to give a sanity check to the visualization
#8: Create Surface Mesh (Surface Nets): Create a triangular surface mesh from the features.
#9: Write STL Files from Triangle Geometry: Write out all the features as independent STL files.