Instructables

Using Meshlab to Clean and Assemble Laser Scan Data

Picture of Using Meshlab to Clean and Assemble Laser Scan Data
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Meshlab is an open source software program used to manipulate and edit mesh data. This tutorial will specifically show how to assemble, clean and reconstruct data from a 3D laser scanner. The techniques used with the scanner used here should apply to scan data from any machine, but first read any documentation included with your system before beginning.

One must use their judgement when scanning the object to be sure to capture enough data to create the best mesh possible. The alligator head used here required around 30 scans taken from various angles. Typical scan sets may be as small as 5 and as large as 50. This was a high number due to all of the hidden geometry inside the mouth. For scans taken with a calibrated rotary turntable, the coarse alignment steps may be skipped entirely. However, it is still recommended to do a fine alignment to eliminate any error inherent to the turntable. As with any software, backup your work and save frequently.
 
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Step 1: Cleaning Scan Data

Start by opening the first scan file. Chances are high that the object will be surrounded by a lot of extra data that does not need to be included in the final mesh. The easiest way to remove this data is to use Select Faces in a Rectangular Region tool. It allows you to use a marquee style selector to choose faces that you would like to remove. After selecting them, go to Filters/Selection/Delete Selected Faces and Vertices to remove them. This not only deletes the faces, but also removes the underlying point data, resulting a a cleaner mesh and smaller file size. Repeat this step for every scan and it is helpful to save the clean file as a new version, leaving the original intact. Save often!
SanderS36 days ago

Hi, I don't have a scanner that provides .ply files but xyz point clouds. It turns out (flattening leaves me with an empty layer) that this procedure fails while it is a points only file.

Do you have any recommendations what to do with the file before I can go through this procedure.

how would i import an obj file and then clean it up to be a manifold watertight mesh ready for 3d printing. thanks.
I see this question was posted a long time ago, but was never answered.

The simplest way to make an object manifold/watertight is to remesh using the poisson reconstruction (shown at the end of this instructable). There are tools out there (i.e. Magics) that will 'heal' a file as well, and let you do it with a high degree of control. Poisson will simply remesh the entire thing, making it watertight along the way. You have less control but it works well... assuming you have a good scan data set to begin with. If you have something with excessively large holes it may make it watertight in ways that aren't unintended.
jam BD2 years ago
Absolutely amazed by the results.
 I'm happy to say that you've succeeded in your goal of getting people interested. Following this tutorial, I built my own scanner...I'm making an instructable and I'll post it soon. Meshlab had worked pretty well for me so far!
kelseymh5 years ago
Very nicely done. This "could" have been considered referral-spam, but you've done a great job at putting together a useful and general tutorial without flogging your own product :-)
3rivers3d (author)  kelseymh5 years ago
Thank you. The goal was not to push a certain product, but to get people interested in scanning. These techniques can be used with any system from a David Scanner on up. If you can not tell, I REALLY like Meshlab which is a great tool and open source to boot!
I definitely could tell, and I also learned that 3D modelled was much more complex and human-intensive than I had realized.