teem	/	mite	Basic miter demo

1. Volume input, image output
   • "-i pin.nrrd -o pin-rend.nrrd", or,
   • "-i sph.nrrd -o sph-rend.nrrd"
2. Camera and image information
   • "@cam.txt"
   This is an example of a hest response file.
3. Lighting and surface properties
   • "-ld 0.3 -1 -2.2 -am 1 1 1 -ads 0.0 0.7 0.3 -sp 70"
   The light direction (ld) above and to the right of the viewer, like an offset head-light.
4. Kernels used in filtered sampling
   • "-k00 cubic:1,0 -k11 cubicd:1,0 -k22 cubicdd:1,0"
   This uses the B-spline for value reconstruction, and its derivatives for derivative measurement.
5. Ray and compositing parameters
   • "-step 0.008 -ref 0.01 -nt 30 -n1 0.99"
   The axis aligned rays will sample the volume about 2/0.008 = 250 times, which should be good for a 64³ volume.
6. Transfer functions We have to do a bit of unu hacking to generate the transfer function:

   echo "0 1" \
    | unu reshape -s 1 2 \
    | unu resample -s = 1024 -k tent -c node \
    | unu save -f text -o ramp.txt
   
   echo "-1.0 0.0   -0.8 0.0    0.8 1.0    1.0 1.0" \
    | unu reshape -s 2 4 \
    | unu imap -i ramp.txt -r -m - \
    | unu axinfo -a 0 -l "A" \
    | unu axinfo -a 1 -l "gage(scalar:v)" -mm -1.0 1.0 -o val-txf.nrrd
   
   rm -f ramp.txt
   

   The first command created a 1024 line file ramp.txt containing the values linearly increasing from 0.0 to 1.0. This was fed into the unu imap with control points implementing a step function, and then unu axinfo sets up the axis information so that mite can use the nrrd as a transfer function. Now we can tell miter:
   • "-txf val-txf.nrrd"

miter -i sph.nrrd -o sph-rend.nrrd @cam.txt \
  -ld 0.3 -1 -2.2 -am 1 1 1 -ads 0.0 0.7 0.3 -sp 70 \
  -k00 cubic:1,0 -k11 cubicd:1,0 -k22 cubicdd:1,0 \
  -step 0.008 -ref 0.01 -nt 30 -n1 0.99 \
  -txf val-txf.nrrd

overrgb -i sph-rend.nrrd -g 1.4 -b 0.2 0.3 0.4 -o sph-blu.png
overrgb -i sph-rend.nrrd -g 1.4 -b 0.7 0.3 0.2 -o sph-red.png

miter -i pin.nrrd -o pin-rend.nrrd @cam.txt \
  -ld 0.3 -1 -2.2 -am 1 1 1 -ads 0.0 0.7 0.3 -sp 70 \
  -k00 cubic:1,0 -k11 cubicd:1,0 -k22 cubicdd:1,0 \
  -step 0.008 -ref 0.01 -nt 30 -n1 0.99 \
  -txf val-txf.nrrd

overrgb -i pin-rend.nrrd -g 1.4 -b 0.2 0.3 0.4 -o pin-blu.png
overrgb -i pin-rend.nrrd -g 1.4 -b 0.7 0.3 0.2 -o pin-red.png

sph-red.png	sph-blu.png
pin-red.png	pin-blu.png

A transcript of all the commands on this page is also available: rend-sph-pin.txt. You can run all the commands by simply saying "source rend-sph-pin.txt" inside any useful shell.