2: MODELING THE ARTERIES
main point I want to make in this tutorial is to explain how to make arteries
that follow the surface of the heart. One of the main uses I have for
this model is to create diagrams of coronary heart disease, which involves
the blockage of the arteries that nourish the muscles of the heart. Therefore
I wanted good quality arteries made of geometry. A bump map would not
be good enough for the close up views I want.
To create the coronary arteries I first began in Adobe Illustrator. I
assembled screen shots of the model form five directions. On top of the
screen shots I drew the arteries.
I was satisfied with the shape of the arteries I used Illustrators
outline stroke command to create closed polygons.
imported the illustrator shapes into Modeler using the EPSF loader plugin.
I extruded the shapes to be deep enough to intersect the surface of the
heart. I positioned the shapes so that they intersected the heart of the
front sides, back and bottom.
made a copy of the heart in a new layer. I used the freeze command to
create a shape suitable for boolean operations. I used the Boolean-intersect
command to cut the artery lines out of the heart shape. I then used the
merge points command with a fixed radius to reduce the number of points
to a comfortable number.
selected the points along each branch of the arteries and used the Make
Open Spline command to created spline curves. The result is that I have
splines that exactly follow the contour of the surface of the heart.
selected a single point at the end of each spline and copied them to a
new layer. I used the Point-Clone-Plus command to copy a group of 3 quads
to the endpoint of each spline.
then selected each group of polygons individually and rotated them so
that the normal pointed in the direction of the spline.
in a tedious and time-consuming process, I copied each spline to a new
layer. Next I hid all the quads except one group. I set the layer with
the corresponding spline to be the background layer.
I used the Rail Extrude command to extrude the polygons along the spline.
I repeated this process for each spline individually.
three different sizes of quads were to help in the tapering of the veins.
To further taper the ends of the tubes I selected each 4 point intersection
and used the scale tool with the action mode set to scale from the selection
joined the tubes together with quads. The plugin PolySew (available from
http://www.m2estudios.com/plugins.html) was very helpful for this step.
Thank you m2e Studios for creating this useful plugin.
arteries textured and converted to subpatch mode.
result of all that work is arteries that exactly follow the contour of
the heart's surface.