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Size of STL StereoLithographic Files

Here is an example calculation of the size of an STL file:

Output size of STL files

PhotoToMesh does the calculation for you. As you change the X samples or Y samples you get an estimate of the file size.

Note that the size of the original photograph or image is irrelevant, it is the "resolution" of the output STL file which changes its size.

The above example has 200 samples on a side. That divides the "front" of the object into 200x200 faces. Each face consists of 2 triangles, and each triangle consists of 50 bytes (in STL files). So the top part of the above object will have

200x200x2x50 = 4,000,000 bytes, just under 4 MBytes,

Now the whole object has 6 faces, and we can just ignore the 4 small sides in this rough calculation, but we have to take account of the back side (hidden in the above image). So the total file size will be 4MB x 2 = 8MBytes. This corresponds with the 7.91 MBytes in the dialog above.

However doubling the resolution quadruples the output size:

STL file size problem and PhotoToMesh

You can see that I've set the output resolution to 400 x 400, and the output file size has gone up to 32MBytes. The final object has a better look to it, but at a cost of file size.

Unfortunately STL imposes some limits on how the triangles can be arranged. Other formats may be able to reduce the back side to one polygon, thus halfing the file size. STL does not permit this.

If you use too much memory PhotoToMesh will give you an "Out of memory" error message like this:

How to reduce STL file sizes (out of memory)

At this point it is better to exit from PhotoToMesh and try again with a smaller size.

However I have been able to improve memory handling, so if you have a version before the 24th March 2013 and see this error let me know and I'll send you have an update.





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