Hi all,
I hope someone of can help me. A few days ago I started
to familiarize with opendx.
My goal is to plot trajectories (pictured with values for longitude,
latidude and height above seelevel) on a map. Importing my ascii files
with the trajectory data is no problem. But how can I, for example, plot
these trajectories on a map of Europe? Is it possible to plot the whole
globe and to overlay my data?
Thanks
Michael
The basic concept is very simple, but may elude beginners until
they've created some nets that employ it. You can have as many
Imports or ImportSpreadsheets or a combination as necessary to import
different data sets. You need to acquire a data set of Europe or the
globe in a form that DX can deal with. Some other people on the list
may be able to point you to those.
Then Import the base map (Europe, say) with one Import and your
trajectories as you are now with another Import (or
ImportSpreadsheet).
To make the two fields overlay properly, ensure that the lat-lon
data is already consistent before Importing:
OR:
After Import, use Mark("positions") (if the lat-lon's are the
positions of the imported data set), followed by Compute, followed by
Unmark("positions") (which puts the transformed values back into the
"positions" component). In the Compute, perform the necessary scale
and transform ops to make the field you are operating on consistent
with the other field (which may be the base map data for example).
You can add more inputs to any Compute so you can feed in scale
values or northings-eastings as needed. Then create an expression
like: "a.x * scale_x, (a.y * scale_y) + northing, a.z)" or whatever
you need. (a is the 3-vector of input positions, so a.x is the
x-component of that vector).
Then perform whatever type of "realization" you want, such as
ShowConnections to show lines connecting positions, then use Collect
to join the two (or more) fields (base map field, trajectory field,
etc.) together to send to Import.
The big concept is that Image can render simultaneously several
different inputs of several different types, so you do NOT need or
even want to try to merge the base map and trajectory data upstream.
Leave them separate so you can do whatever you want to them
independently, including, bringing in a different trajectory data set
tomorrow or next month without having to change anything in the net
except the input file name.
--
Chris Pelkie
Vice President/Scientific Visualization Producer
Conceptual Reality Presentations, Inc.
30 West Meadow Drive
Ithaca, NY 14850
[EMAIL PROTECTED]
