On Fri, May 16, 2008 at 02:10:19PM -0400, we recorded a bogon-computron collision of the <[EMAIL PROTECTED]> flavor, containing: > If my memory is correct, there is some method to send area "shapes" with APRS. > I've got it in my mind that firenet sends something like this for weather > data. > > I was wondering, is it possible to use similar techniques to transmit a > shapefile? Specifically, I have a bicycle route for an upcoming event that I > would like to share with others via APRS. Is this possible?
The wxsvr "shape" information only supports a limited number of points, so it would not be straightfoward to send a whole shapefile over APRS. That information is passed in an object's comment field using a string of characters to represent each vertex. As such, it is limited to the length of the comment field, which works out to a maximum of 16 points if you put nothing else in the comment. Since wxsvr puts information about the area into the comment as well, their objects tend to be less than 16 points. If you care to chop your route up into segments of 16 points or fewer, you could transmit your route as a collection of objects. There is a routine I wrote in util.c called "makeMultiline" that is currently unused in xastir. It takes an array of lat/lon points and constructs the string needed to transmit that as a multiline object. It also computes the center of the bounding box of the points, and this is meant to be used as the coordinates of the object point (from which the other points are represented as offsets). I have occasionally used that routine in a standalone code to generate the text for a multiline object, then cut and pasted it into the object creation dialog box in xastir. I put it in xastir's source code because it seemed someone might want to do something with it someday, but so far it hasn't been used. Maybe you'd like to try. -- Tom Russo KM5VY SAR502 DM64ux http://www.swcp.com/~russo/ Tijeras, NM QRPL#1592 K2#398 SOC#236 AHTB#1 http://kevan.org/brain.cgi?DDTNM "It's so simple to be wise: just think of something stupid to say and then don't say it." --- Sam Levinson _______________________________________________ Xastir mailing list [email protected] http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
