Re: Using ISL to create images


Hi Sara,

I am new to using IDV and I am trying to create images using ISL.

I have been working through examples in the IDV User's Guide and Tutorial. The example ISL file display.isl comes closest to what I want to do, but I cannot get this ISL file to run properly. I don't know how to create the template.xidv it needs.

The xidv files are "'bundle" files which are what the IDV saves off to capture and recreate the application state.
When you are running the idv simply go to the File->Save As... menu.
You will be prompted for a bundle file name. You can then load in that bundle file later to
recreate what you were looking at.

As a convenience you can also do a File->Save As and enter a ".isl" file name. This will save off the bundle xidv file as normal and also generate an example isl
file that loads the bundle in and creates an image or a movie.


It looks as though you are using the <datasource> and <display> tags in the isl to create your imagery. A caveat with those - those tags have not been exercised very well and I am sure there is lots of missing
functionality. We are always looking for input on what is missing, etc.

I'm not sure what your requirements are but you might want to start off with the isl/bundle combination described above. This allows you to create exactly the displays you want interactively and then capture them later with the isl. There are facilities in the isl to switch the data sources (e.g, from one ruc file to another) that are being loaded.

I am having trouble creating an ISL file to generate images for various parameters in a data source. For starters, I am using small_ruc_grid.nc simply because it is available to use. Here are some questions I have:

1) Is it possible to get some example ISL files for how one can create images to answer the below questions using small_ruc_grid.nc or some other readily available file?
The best source right now is the user guide ISL section:
http://www.unidata.ucar.edu/software/idv/docs/userguide/isl/DataAndDisplays.html

We are intending in the next month to make available more example isl files and better examples of generating real time imagery.

2) How does one list all possible values for "param" and "type" to use with a dataset?
For the available parameters that is best done by loading the data file into the IDV and looking at the available fields in the Field Selector. For the display types I am attaching a listing of the types and their description.

3) How does one determine the range of valid values for each parameter? For example, if I want to create a contour plot for temperature, how can I determine the minimum and maximum temperature values that are used to create the contour plot?
For contouring the idv uses
4) How are color filled contours and color shades specified from an ISL file?

You can set the contourInfoParams property in the display tag. There is an example of that in the userguide section. For color shading you can set the colorTableName property in the display tag.

Are there other types of 2-D imagery one can create with ISL? If so, what tags are needed? What about tags for the various 3-D imagery types?
All displays are created with the <display> tag. The available displays types are in the attached file.


5) If I want to write multiple images from one ISL file, how do I clear the display between images?
That is a really good question. Normally when a bundle is loaded by an isl script all currently loaded displays and data are removed. However, right now there is no way to explicitly remove displays and data directly from the isl. We'll add that in this week.


6) Eventually, I would like to create images from GRIB files. Do any of the answers to the above questions change when using GRIB files instead of netCDF files? Also, among the files that one can access with IDV, which ones, if any are GRIB files?
There shouldn't be any differences. The IDV treats GRIB just like gridded netcdf files.

-Jeff

imagesequence Image display
planviewcontour Plan view contour plot
planviewcontourfilled Color-filled contour plan view
planviewcolor Plan view color-shaded image
imagecontrol 3 Color (RGB) Image
radarsweep2d Radar sweep view in 2D
radarsweep3d Radar sweep view in 3D
rhi RHI
level2CAPPI CAPPI
radarvolumescan Volume Scan
radarisosurface Radar Isosurface
contourxs Contour cross section
contourxsfilled Color-filled contour cross section
colorxs Color-shaded cross section
dataxs Data Transect
trackcontrol Track Colored By Parameter
planviewflow Plan view of flow vectors
streamlines Stream line plan view of flow vectors
planviewflow3d Plan view of 3D flow vectors
windbarbplan Wind barb plan view of flow vectors
flowxs Cross-section of flow vectors
flowxs3d Cross-section of 3-D flow vectors
windbarbxs Cross-section of wind barbs
streamlinesoverz Streamlines over topography
topography Topography
isosurface 3-D Isosurface
isosurfacebyanother Isosurface colored by another parameter
planviewcontouroverz Plan view contour plot on topography
planviewcontourfilledoverz Color-filled contour plan view on topography
planviewcoloroverz Plan view color-shaded image on topography
imagecontroloverz 3 Color (RGB) Image over topography
profile Vertical Profile
vprofile Vertical Profile (new)
probe Data Probe
timeheight Time/Height Display (Contours)
timeheightshade Time/Height Display (Color Shaded)
timeheightflow Flow Time/Height Display
timeheightbarb Wind Barb Time/Height Display
timeseries Time Series Display
raob_skewt Skew-T for RAOB data
raob_stuve Stuve for RAOB data
raob_emagram Emagram for RAOB data
profiler_timeheight Time/Height Display
profiler_planview Plan View
profiler_3d 3D View
track_skewt Skew-T for tracks
track_stuve Stuve for tracks
track_emagram Emagram for tracks
grid_skewt Skew-T for grids
grid_stuve Stuve display for grids
grid_emegram Emagram display for grids
textdisplay Text/HTML display
chatlogdisplay Chat Log Display
moviedisplay Movie Display
stationmodelcontrol Point Data Plot
obslistcontrol Point Data List
shapefilecontrol A shape file display control
rangerings Range rings and radials
rangeandbearing Range and Bearing between two points
mapdisplay Map Display
notecontrol A text note
locationcontrol A display of station locations
curvecontrol A drawing control
drawingcontrol A drawing control
frontdrawingcontrol Front display
filedrawingcontrol A drawing control
transectdrawingcontrol Transect drawing control
locationindicatorcontrol A locationindicator
wmscontrol WMS Control
bgwmscontrol Background Image
imagemoviecontrol WebCam display
imagemoviecontrol2 Image Collection
worldwind WorldWind Locations
volumerender 3-D Volume Rendering
omni A Visad spreadsheet display