Saturday, 19 July 2014

Shame

I'm going to try and create a sculpture based on this picture next. I like the off-balance lines, the hidden face and the twisted shape.



The photo is by Tomas Rucker and is called 3 in his White series of nudes.

Here's the model I have created so far, viewed in Blender. The pose is clearly not identical but you can see where it takes its inspiration from.



When I came back to work on this pose I wasn't happy with it. The sinuous nature of the original pose had almost completely gone and the new hand position somehow changed the story. I decided to do some more work on the posing.



Then I thought it might be interesting to document the steps needed to make a posed model printable.

Hide the hair
Remove the eyelashes

Circle select eyes and mouth in side view

Shift-H hides everything else. Trim out the eyes and mouth and close up the holes in the mesh.

Hair models in character posing software are almost always totally unprintable items. I have found that the quickest way to make them printable is to use the ShrinkWrap modifier on a dense Isosphere placed in a position surrounding the hair model. Then using the project option in a negative direction, you can send all the points of the sphere inwards until they meet some point on the hair, leaving you with a single water-tight mesh. Some fairly intense smoothing removes all the jagged edges and leaves a very passable, and printable, copy of your chosen hair design. 



This just needs Boolean merging with the head which usually works OK, as long as the eyes and mouth have been fixed first. 

Now we need to deal with overlapping limb parts. There are several ways of doing this.
1. The quick and dirty method.
Use Autodesk's Project Miller to re-skin the visible external surface which hides any internal overlaps.
2. Use sculpt mode to flatten overlaps from the inside.
3. Use Boolean union to eliminate the overlaps. This option is interesting but doesn't work on a single mesh with overlapping parts. So why not just chop up the parts into separate meshes? Worth exploring, I think.

I started at the feet and worked upwards, using option 2 to eliminate any of the areas where the mesh of one limb poked through another. There is a typical example where the thighs cross. I used Box select to highlight all the affected vertices and then Shift-H to hide everything else.



From the inside you can see the bulge of the left thigh poking through into the inside of the right thigh, and vice versa.



I started by changing from Edit mode to Sculpt mode and then using first the Flatten brush and then the Smooth brush on the bulge to make it disappear. 



By working from both sides I could keep the contact area flat.



This works well where there is a small bulge across a large area, but is less effective where a larger, more complex part needs removing. So for the intersection of the arms and the left breast I decided to try a different tack and used option 3.

I rotated the model by 35 degrees around the vertical so that a horizontal plane would neatly bisect the upper arms. I then loaded the model into NetFabb which has a very nice plane cut function which provides a kind of X-ray preview of the slice before making the cut.


My cunning plan was to slice the model into a number of separate parts, make each one into a separate water-tight mesh and then Boolean merge them back together thus dealing with a number of complex overlaps at a stroke.



After making the cut, each half needed to be saved separately. The forearms, in the lower half, could then be selected and split off into a separate model. Here is the main torso piece.



My plan worked almost perfectly, only failing when the last piece in the sequence refused to Merge with the rest. I suspected that this was because the Boolean engine was struggling to cope with the intersecting parts and closing the loop of a torus and recognising the relative inside- and outside-ness of both ends at the same time. I fixed that by making another thin cut that took a slice out of the arms in an area with no complex intersections. Using that slice as the final merge then worked successfully. 

I added a simple bevelled cylinder to the base to make a stand. Eventually, I had reached the point where the only crossed meshes remaining were in both armpits. I spent a fairly lengthy mesh-editing session trying to clean up the mess but finally decided to take the easy way out and used Project Miller to re-skin the model for me. Don't know what I'd do without that bit of kit!

The main reason for going to all this trouble with the model was so that I could use Simplify3D as my slicer. Cura is better at handling faulty meshes but Simplify generates better support material that breaks cleanly away after printing.

I had intended to print this model on my tall delta printer, but it isn't coping well with this hot weather and the motors seem to be prone to skipping steps. So I went back to the Mendel90 and printed a small test version.

3D printed version in coffee-brown PLA before and after removing the support material.




Just like Pensive, one of my earliest works, the fingers are only slight wider than the extruded filament at this scale. It really needs to be printed twice as big as this. As soon as the cooler weather returns I'll try again on the delta printer.