When writing my third year dissertation a few months ago I analysed a basic method of creating photogrammetric models using 123D Catch, and when it came to discussing the later editing of the models the program I turned to was Meshlab.
I’d originally come across this program when looking at the Ducke, Scores and Reeves 2011 article, as part of a more complex method to actually create the models, but had concluded that it would have a much better use as a separate process. This is due to the vast variety of tools and filters that the program employs, which surpassed those of any other freeware 3D program I knew. I talk in the past as I’ve since changed my mind, at least in part.
But before talking about the problems, I’ll go through the advantages:
- Easy interface: Simple operations are easy to do in Meshlab, and the navigation is efficient (the zoom is counterintuitive, still easy to adapt to it). Loading models is simple and it does allow a lot of file types to be used, plus changing between points and surfaces requires a simple button click.
- Nice lighting: Far from complex or complete, the lighting tool is somewhat primitive, but possible for the best. Programs like Blender or Sketchup make me go insane when you just want to emphasise a certain area, while Meshalb has a light you can rotate to show certain elements. It also makes the model’s edges come to life, increasing the contrast and bringing out things hard to see otherwise. When I made a photogrammetric model of a Zeus head statue, some of the other archaeologists with me suggested by looking at the Meshlab light effect, that it may well be a Neptune head instead.
- Alignment tool: I think this may be due to my ignorance of Blender, but I still prefer the way Meshlab glues together two models, by selecting 4 identical points between them. It adapts the size and orientation automatically, with good results.
- Great filters: I wrote an article about using the APSS filter to bring out inscriptions, and there are many more available, with references to documentation about them. Some are a bit useless for what I’m trying to achieve, but still not bad at all.
- Free: Meshlab is entirely open source, which is great for making Photogrammetric models. Compared to program’s that are commercially available, it still does what you need it to do, without having to pay the money.
There are however some problems:
- No undo button: Probably not the major issue, but by far the most annoying. The number of times I’ve had to start a project from the start due to a minor issue makes this a big flaw. Unless you save every time you do anything, you’ll find yourself in trouble.
- Saving glitches: Quite a few times I’ve saved the final product, closed the program and opened it again to find it had not saved textures. This is a difficult thing to get around when we are dealing with Photogrammetric models, where the texture is essential.
- No image files: Meshlab seems to hate all image files, which makes it difficult in some scenarios. For example it is not possible to open a models and an image in the same context. I found this frustrating when gluing together some features from then same trench, where I wanted to use the plan of the trench as a guide to the positions.
- No real rendering: Blender is great to create good images of the objects you’ve created, while with Meshlab all you can do is use the windows Snipping Tool. Presentation wise it is deficient.
- Inefficient tools: In some tool Meshlab excels, in other it is lacking. The measuring tool exists, but in order to set a reference distance you have to go through a series of calculations that you personally have to do. The rotate tool is odd, and the transpose tool only seems to apply to a single layer.
Overall Meshlab can get the job done, and in some things it can work better than with other programs such as Blender. However the issues that derive from the fact it is freeware makes it hard to use. I would still recommend it, but when it can be avoided it’s probably for he best.
Ducke, B., Score, D. and Reeves, J. (2010) Multiview 3D Reconstruction of the Archaeological Site at Weymouth from Image Series. Computers & Graphics, 35 . pp. 375-382.