STL TO POINT CLOUD HELP PLEASE

[GARTH LEE]

USING DESKCNC WITH A TP100 PROBE, DESKCNC GENERATES A .STL FILE. IS THERE ANYWAY OF GETTING AT THE RAW X,Y,Z DATA SO I CAN USE THIS TO GENERATE A X CELL FILE TO MAKE UP THE DATA REQUIRED FOR A POINT CLOUD.
ANY HELP/SUGGESTION WOULD BE GREAT

[ger21]

As long as it's not a binary .stl, open it in Notepad.

[creasyts]

Dear Garth:

I've done this many times. Follow ger21's advice and save the STL as an ascii file.

STL files define triangles in 3D. Three XYZ points define each triangle. Interior triangles--that is, triangles away from a free edge--share some common points. This makes some points appear several times. My CAD software did not like this. It wanted each point to appear once. Perhaps your point cloud should be like this.

I had a workable, silly way of getting each point to appear once. Someone, perhaps Fred of IMSRV, told me that Excel can hide repeated points--with a data filter--and that is the way to go.

You have to edit the file in notepad and word so that excel won't choke on it. Then do a three level sort on x, y, z, so the repeated points appear together. The menu commands are Data/Sort/By ___, then by ____, then by ___ where the blanks are the x, y, and z columns.

Then select the columns--column headers are good for sorting and required for filtering--and select DATA/FILTER/ADVANCED FILTER. Check the Unique Records box and click OK. The select all, Copy, and Paste the data into a new spreadsheet. You should have a point cloud with each point appearing once.

You can save as comma or tab separated values to keep your software happy.

Terry

[Andre' B]

Here is a description of the STL file format.
http://mech.fsv.cvut.cz/~dr/papers/Lisbon04/node2.html

I have been going to work up a VBA function to read the binary format into a worksheet but it's one of those things I never seem to get done.

[creasyts]

Dear Thread:

Thanks to Andre B for the link to the file structure definition.

There is also wikipedia:

http://en.wikipedia.org/wiki/STL_(file_format)

If one loads the text file into excel and sorts it, the vertex lines move to the top and we can delete the other
lines.

Save this as a text file.

Use a text editor or word processor to replace 'vertex' and the space after it with nothing--that is, delete it.

Replace all spaces with tabs--search for space and replace it with ^t.

Copy the text and paste it into excel, then sort and filter
the points.

I hope that we are helping garth lee.

Regards.