This is quite similar to, though far simpler than, the way galaxies were processed. So we won't repeat stuff already said there.
These were got from the SDSS servers using the SQL command :
select all s.ra,s.dec,round(s.z,7),p.petroRad_r,p.petroMag_r from specObj s join photoObj p on s.bestObjID=p.objID where (specClass=3 or specClass=4)
We obtained this in HTML format, saved it as a plain text file "sloanquasars.dat" and stripped initial headers so Matlab could read it. There is no corresponding value like eClass to distinguish between types of quasars, so the samme picture was used for all of them.
Open Matlab, and make sure the .m files above are in your path (with an addpath command or using the GUI). Then type
Q = load ('sloanquasars.dat'); petmag = Q(:,5); ok = find(petmag > -9999); Q = Q(ok,:); M = radecz2xxyyzz(Q); petmag = M(:,5); dist = M(:,6); z = M(:,7); al = -0.5; kcorr = -2.5 * (1+al) * log (1+z) / log(10); lumdist = (1+z) .* dist; absmag = petmag - 5*log(lumdist)/log(10) - kcorr - 25; lumin = 100.^(-0.2 * absmag); M(:,8) = ones( size(M,1), 1); M(:,4) = -absmag; M(:,5) = lumin; save sloanquasars.speck M -ascii
See the instructions for galaxies for details of the luminosity calculation.
This command results in a G x 8 matrix representing G quasars with for each quasar
So now you have a text file sloanquasars.speck that has all the galaxy positions, picture types (labels), and orientations. This is almost Partiview speck file format, but you need some headers. Open sloangalaxies.speck in a text editor and place the following lines at the start of it.
datavar 0 mag datavar 1 lumin datavar 2 dist datavar 3 redshift datavar 4 pictype texturevar pictype texture -a 1 halo.sgi
You should also create a CF file, say sloan.cf, with the following parameters. You can change the parameters - read the Teuben-Levy Partiview manual for some documentation on what parameters mean. Or guess and tinker and guess and tinker...
The following was then added to the CF file used for the Sloan galaxies:
filepath +:. object g11=quasars include sloanquasars.speck eval psize 1000 eval ptsize 2 10 eval lum mag 0.4 10 eval polylum mag 0.4 10 eval slum 1 eval polysize 10 eval polysides 4 eval polymin 0.1 20 eval alpha 0.99 eval color exact 1 0.5 0.5 eval points off eval poly on eval label off