| How to make GIF file (2) ? [message #4531] |
Mon, 12 June 1995 00:00 |
bleau
Messages: 24
Registered: November 1993
|
Junior Member |
|
|
Hi again. I posted a message last week re generating a GIF file from IDL so I
can serve it over WWW, and received quite a few responses so far. All of them
have directed me to use TVRD and WRITE_GIF. Thanks to those who responded.
This does not, however, solve my problem entirely. Here are the additional
details.
I had learned about TVRD and WRITE_GIF from TFM before I posted my initial
message, and had hoped there was a better way of approaching the problem (like
with a PLOT option). I put up a simple plot and called TVRD(0,0,100,100,0),
followed by a WRITE_GIF. I moved the resultant file to my WWW server
directory, went to my Mac, fired up Netscape, and viewed the image. It was a
small square image in the corner of the graph, showing the axes. So far, so
good. I next called TVRD(0,0,200,200,0) and put it in another file. This
displayed a rectangular image with some lines, but was not recognizable as part
of the graph (well, maybe if you strain). The rectangle was roughly twice the
width of the first subimage and half the height, though I wouldn't swear to it
(I didn't measure it). Finally, I tried it with TVRD(0,0,500,500,0), and when
viewed this produced a *blank* image! There's something going on here I do not
understand, folks, and it puts a big question mark beside the entire process.
The second problem is one of automation. As I mentioned earlier I want these
graphs to be served out over WWW. What I didn't mention in my earlier post was
the method I had in mind. I'd like these graphs to be generated when a WWW
request comes in for data in a certain time frame. My HTTP server would fire
up an application which would figure out what raw data files are needed, then
start up IDL and feed it the data. IDL would generate a GIF file, which the
application would then feed back to the HTTP server and thence to the WWW
client. So, IDL would be running in a detached mode, with *no* display device.
Question: Can TVRD get information from the display device if there is no
display device?
Also: Can PLOT be made to generate a plot (which TVRD can access) if there is
no display device? I know PLOT can be told to generate a PostScript file (do a
SET_PLOT,'PS'), but this doesn't help, as Netscape doesn't know how to display
PostScript. Ideally, I'd like to do the equivalent of SET_PLOT,'GIF', but that
doesn't appear to be an option. If the PLOT-TVRD combination doesn't work in
this mode, what can I use on PLOT to eventually get a GIF file? Thanks.
Larry Bleau
University of Maryland
bleau@umdsp.umd.edu
301-405-6223
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
