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Re: magnify factor


LAS uses Ferret as the back end visualization and analysis package and the default Ferret installation comes with several default 'ETOPO' datasets that are used for the land mask.  The highest resolution of these is etopo20 which is at a resolution of  20 minutes.  The reason we don't distribute higher resolution files is that they are very large and we expect people with a regional rather than a global focus to have access to the appropriate bathymetry/topography datasets for their respective regions.

Easiest fix --

To customize your LAS so that it uses a higher resolution land mask you should begin by making a copy of std_gif.tmpl so that your changes are not overwritten when you upgrade LAS in the future.:

  cp las/server/jnls/std_gif.tmpl las/server/custom/chesapeake_std_gif.tmpl

Modify the chesapeake_std_gif.tmpl file to have it use the etopo05 dataset when the 'magnify' attribute is '4' or higher.

  [% ELSIF magnify == 3 %]
     go fland 20
  [% ELSIF magnify >= 4 %]
     go fland 20

  [% ELSIF magnify != -1 %]

Now, of course, you'll have to download the etopo05 dataset.  You can get it here:


Be careful as there is some inconsistency of naming:  'etopo5' vs. 'etopo05'.  You will want the file to be named 'etopo05'.

Now you need to add some configuration to the dataset.xml file for your datasets telling LAS to use the modified chesapeake_std_gif.tmpl for these datasets.  General instructions are here:


You will need to include the following in your dataset.xml files:

Then regenerate the LAS user interface and you should be off and running.

Higher resolution --

If you want even higher resolution you will have to create your own (much simpler) version of  the fland.jnl script to utilize the dataset and variable of your choosing.  The IRI has a 30 second resolution available via OPeNDAP but you probably don't want to download the whole thing:


I hope this puts you on the right track.

-- Jon

Enils Bashi wrote:
Dear las users,

Does anyone know how to tweak magnify factor in
$LAS_DIR/server/jnls/globe_gif_xy.jnl to get a higher resolution on the map
applet over land and coastal areas?
Any and all feedback would be greatly appreciated.

Enils Bashi
Programmer - Chesapeake Bay Program
Veridyne Incorporated
Annapolis, Maryland: (410) 267-9833


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