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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
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To learn about what's going on, see About the Archive Site.
Hi Marius & Bill, On Wed, Jul 14, 2010 at 7:50 AM, Bill Hibbard wrote: > Can any active VisAD programmers suggest tools > to help define J3D matrices? > As part of VisBio, I wrote some helper methods to zoom, translate and pan a display. They take care of applying the correct 4x4 matrix to the projection control (using DisplayImpl.make_matrix). You can find the code here: http://www.loci.wisc.edu/trac/java/browser/trunk/components/visbio/src/loci/visbio/view/ViewHandler.java?rev=5093#L124 Cheers, Curtis On Wed, Jul 14, 2010 at 7:50 AM, <hiding@xxxxxxxxx> wrote: > Hi Marius, > > We are all glad that you like VisAD. Your questions > are excellent. Here is what I know about answers to > them (but cavat emptor, I haven't written any code > for 6 years): > > 1. a) Images are rendered via texture maps, and > Java3D texture maps require values for each of > red, green and blue (and alpha) at each pixel. > > 1. b) Java3D does not support hardware color > tables. (I first wrote Vis5D on the Stellar GS 1000, > which did support hardware color lookup tables, > missed that capability in most later graphics > hardware). > > 2. You should be able to do this via the setMatrix() > method of the ProjectionControlJ3D you get from > DisplayImplJ3D.getProjectionControl(). Of course, > you've got to figure out how to set a user view point > as a 4x4 matrix. > > Can any active VisAD programmers suggest tools > to help define J3D matrices? > > 3. Applications would need to keep track of > progress through a sequence of fetch, analyze and > display data. It would be nice if the display "please > wait" would give percent done, but sorry to say it > doesn't. > > 4. a) Perhaps the Unidata folks can help with this > (or perhaps Tom W)? > > 4. b) Jeff McWhirter recently created the CachedFlatField > and related "Cache" classes, that I think are better than > the olf FileFlatField. Hopefully he or someone can > comment on these. > > Best regards, > Bill Hibbard > > > -----Original Message----- > From: Marius Schmidt <mariuss@xxxxxxxxxxxxxxxxxxxxxxxxxx> > To: visad@xxxxxxxxxxxxxxxx > Sent: Wed, Jul 14, 2010 6:14 am > Subject: [visad] HowTo Questions: gray scale, shader gray scale, viewers > position, process monitor and netcdf access to large files > > Hi again VisAD community, > > as my work progresses I fall more and more in love with the ease of use > of the VisAD library :-). But for today I do not only have laud but also > a bunch of questions I hope you can help me with: > > 1. Gray Scale: > a) I have learned from the tutorial and documentation, that I have to > create a custom lookup table to provide a gray scale mapping using > Display.RGB(A). If I only map to gray in a 3D display I was wondering, > if internally 24 (32) bit texture are used nevertheless? If yes, is it > possible to enforce the use of an 8-bit luminance texture instead to > reduce memory consumption and allow bigger datasets uploaded to GPU memory? > > b) Before I started working with VisAD I experimented with some fragment > shader based application of lookup tables as explained in some > literature. I searched the library for the usage of Shader programms but > did not find any. Am I guessing right that color table is applied to > data before uploading it to the GPU? At which place might it be possible > and a good idea to implement a shader based lookup table for real-time > coloring of depictions (by only exchanging the lookup map stored as > lookup texture in GPU memory and accessed by a fragment shader)? > > 2. Viewers position: > I have not found a way yet to Setup the initial users view point viewing > direction, I guess I overlooked something, can you help me out ? > > 3. Process monitor > Some calculations or data fetching processes in VisAD take longer than a > few seconds and I would like to display their progress using a process > monitor showing the user, that there is still something going on. I have > seen, that as soon as the display is up and there are calculations going > on a "please wait" message is being displayed. But that does not work > for initial pre-displayed processes like fetching and analyzing data of > a bigger Netcdf dataset. Is there a hook to ask Visad how many percent > of a job is already processed ? > > 4. Netcdf > a) I have seen that there is Plain as a reader for NetCDF datasets. I > transformed one of the dicom image sets available at the human visible > project into netcdf format, but without attention to any convention like > CF. Following the VerySimple and Simple example of the developers guide > did not really worked for me, so I set the MathType, FunctionType and > Set informations up manually and handed them over to a FlatField. Then I > used Plain only to read the sample values from the netcdf file into the > FlatField in reversed order. It works allright but I am wondering what > to keep in mind, that the plain reader works innately. How do I have to > prepare my NetCDF files, which conventions are known to Plain? > > b) I shall try to visualize some of the measuring results of the > Coltrims experiment (for your interest: > http://hsb.uni-frankfurt.de/web/research/atomic/coltrims/). > Unfortunately the data files come in chunks of more than 10 GB each. I > found that there are classes called VirtualData, FileFlatField, etc. and > hope, that my guess is right. Are they are somehow intended to be used > for accessing datasets that do not fit into memory? How do I utilize > them for fast retrieving of slices in dimension of 500MB? I do not have > the heart yet trying to access one of those files, because I did have > not really understood, how to use them, and I do not want to freeze my > system instantly :-D > > Best regards, > Marius > > _______________________________________________ > visad mailing list > visad@xxxxxxxxxxxxxxxx > For list information, to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ > > > _______________________________________________ > visad mailing list > visad@xxxxxxxxxxxxxxxx > For list information, to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ >
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