Knight Helmet Scanning
I’ve been wanting to mess around with David Scanner for a while but it only runs on windows and I’m hardly ever around a Windows machine. Since it’s the weekend, I was able to hijack Marisol’s computer and give it a go.
I went to the corner store and bought a model of a knight’s helmet to scan. The helmet was silver and we just happen to have spray chalk, so I sprayed it down with the chalk and that made it nice and matt and perfect for scanning. Reflective things are bad for scanning because they reflect the laser line. Spray chalk is great, but I had to do some touch ups because it rubs off very easily.
I acquired a laser level and a webcam and then began the setup. There is some preparation involved. You have to assemble a model of a backdrop and then get all the pieces in place and go through a set up calibration process. Once I did all that, which took a few hours of reading the manual and getting everything adjusted, I swept the laser line over the model and it makes a point cloud.
I saved an stl file and even though I was using a super high resolution webcam (720×1240) it downconverted it to 320×240 because I don’t have a license. I made three different scans, one from the front and one from each side and then spent about 2 hours learning how to mesh them together in the David Scanner software only to find out when I went to save that this is an option that only works if you have a license. It’s clear in the documentation that this isn’t a free feature, but I wish I had a heads up before I spent all the time meshing the stls together.
In steps Meshlab to the rescue. It’s an open source program that does joins meshes! With Meshlab I was able to take my low resolution stl files and put them together and then do a poisson thing that brings them all together into one mesh. I ended up with an stl model that looked like a very low resolution copy of the knights helmet.
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5 Comments so far
Bob Mottram
It’s an interesting problem. Another approach would be to have a rotating table – maybe an old record turntable – which you put the model onto. You could then manually rotate the table with the camera taking pictures from one side. Some image processing could then be used to extract the silhouette against the background and stitch those together to produce a model. The camera would need to be calibrated, but there are existing pieces of open source software which can do that.
TroyGeek
I too have been put out/ put off by the fact that David scanner only works in windows so I embarked on a quest to find a solution that works in mac or linux. I found a very promising solution for linux called voodoo. it is a free program and works with blender. I have not tried it out yet, I will as soon as my lego rotating table is complete. here is a link that you may find very interesting. http://www.youtube.com/watch?v=vbvex7maHL8
hope to hear how this works out for people.
TroyGeek
Eric Albert
A truly open source, complete system seems to be in order — with decent resolution would be a nice complimentary package to the Cupcake CNC. I also find this approach interesing — http://milkscanner.moviesandbox.net/ and it is open source with Mac and Windows versions available.
TroyGeek
There are other opensource projects for linux called scan3d, scandraid and one called nuages. I have downloaded them but have not had the time to really take a look at them. I think they are hosted on sourceforge.
Ian Johnson
Bob,
There is a program that does that, called 3DSOM (www.3dsom.com) which creates objects from silhouettes. You place the object on a stand above a round calibration pattern on a turntable. It does a really good job depending on the quality of the outline you create, which depends a lot on lighting and background. Photoshop Elements has some great selection tools to help with that. It creates a texture map from the photos and makes a nice looking model. However it doesn’t work well with objects with a lot of concave features that don’t show up in an outline, such as a dish.
What kind of mount is holding the web cam? It looks very versatile.