This project began as an experiment with friends to create a 3D printed mask for Halloween. We did the photo shoot on Halloween afternoon and had a printed mask before dark.
I uploaded about a dozen photos from the shoot to 123D Catch. Although the mesh was full of bumps and other weird protrusions, the printer - a Type A Machine - produced a fine, organic mask. The mask shown above (from Science Hack Day) is unedited, aside from the trimmed edges.
Here are the steps to create this quick mask. I think of it as a platform - a custom-fit base, upon which to add other things: horns, fangs, glasses, etc.
photo source: http://www.flickr.com/photos/mbiddulph/8160242325...
Step 1: Material List
Step 2: The Photoshoot
I used a Nikon digital SLR, but a basic point and shoot, or modern mobile will work.
Location: Because it was an overcast day, we shot outside. That's ideal. Otherwise, even illumination indoors works too. Our background lighting from the first frame to the final frame was fairly consistent, so no post-processing was needed. Sufficient natural lighting is important, since you don't want to use a flash.
Camera settings: I set my camera to capture small, normal JPGs (about 700k each). My aim was to capture the highest resolution possible without incurring delays as my camera wrote to the flash card. I was also motivated to do a reasonably quick upload. I had good depth of field, which is critical not only for the subject, but also to keep the background details sharp.
The Shoot: I started at one profile and swept around to the other side, capturing a bit over 180 degrees. Be sure not to zoom mid-sequence. Although 123D Catch works with up to 70 photos, a person can't sit still that long - so aim for a dozen or so sharp images.
Model tips: Slick down stray locks of hair in advance and avoid shiny and transparent things. The best time to blink is right after an exposure. So, an audible shutter comes in handy as a blink cue.
I was fortunate to have such an awesome model. Thanks Chris ;-)
Step 3: Upload to 123D Catch & Process the Photos
Open 123D Catch online, here. Select Start a New Project and then Select Photos, or drag the photos (JPGs) into the box. After a few moments, the thumbnails will be displayed. Select the Capture Resolution. I selected High. Then, hit Process Capture.
When processing is complete, the progress bar turns into a checkmark. Click on the new project and then hit Open Selected Project. 123D Catch will display "Working - Validating 3D model". You may need to refresh the browser, if this seems to take a while.
Step 4: Download the Mesh
When 123D Catch finishes processing, download the model.
123D Catch does have tools to edit in the browser, but for this tutorial we'll download and make edits locally. I selected the Mesh Package to download because I prefer the OBJ format for 3D editing.
Step 5: Import into Netfabb Studio Basic
Open netfabb Studio, and select Project > Open. netfabb Basic is free and available for download here.
Select the 123D Catch mesh you just downloaded in the previous step. The filename is mesh.obj.
Step 6: Position the Mesh for Easy Editing
We'll cut away all the parts we don't want, leaving a mask. But first, we can orient the mesh it make clean cuts and speed up the process.
Step 7: Slice Off the Extra Parts
Adjust the Y slider (under Cuts) until the vertical indicator is positioned roughly where the mask edge should be. Select Execute cut. Under Cutting options, uncheck Triangular cuts. This is important because we want only the shell at this point. Then, select Cut.
Repeat the above steps to change the view, rotate, and cut until only the desired mask shape remains.
Tips: Make sure the right part is selected under the Parts menu. The current selection will be displayed in green. Experiment with cutting on the X, Y and Z axis. For example, to cut off the top and bottom, experiment with the Z axis slider. Experiment with different views, such as Top, Bottom, Left, or Right, if needed.
To get an angled cut - such as along the jawline - rotate the mesh ~40 degrees or so, prior to the cut. (I rotated the mesh +45 degrees on the X axis.)
Step 8: Remove Cuts (optional)
Next, let's remove the parts we just cut off. This is an optional step, and just to keep things tidy.
Step 9: Export the Mesh
Right click on the mask and select Export part, and then your preferred file format. Wavefront OBJ is a good choice.
If you see a big red triangle with an exclamation point in lower right corner, that's because the mesh is not yet watertight. It's still just a shell and "open". We'll fix that in a moment when we give the mesh depth with an extrusion.
Step 10: Smooth (optional)
The 3D printer we used, a Type A Machine Series 1, did a fine job of creating an organic surface from an unedited, rough mesh. If you do want to smooth your mesh, this is the time to do it: after slicing unwanted parts and before adding depth.
Meshmixer includes brushes to smooth, push in and out, and other surfacing tools. It's free and downloadable here.
Edit one side only, split the mask down the middle, delete the unedited side and then mirror the edited half. Be sure to smooth all along the center seam from top to bottom. In meshmixer, SmoothBrush/1 with strength 20 is a good place to start.
Step 11: Add Depth
Next, we'll add depth by way of extrusion. This is based on meshmixer07, OSX version.
set Offset between -.02 and -.05
set Direction = NORMAL
set EndType = OFFSET
Step 12: Repair and Export a Print-Ready File
Select Inspector from the top meshmixer menubar. Then, AutoRepair All.
Select File / Export from top menu, saving to SLT (ascii or binary format).
We are now ready to print!