[aprssig] Can YAAC or APRSIS32 do a CAVE.JPG map?

Andrew P. andrewemt at hotmail.com
Sun Nov 18 14:07:59 EST 2012

Nice wording, Steve.

This is why YAAC keeps the OpenStreetMap data in vector format and renders it "on-the-fly" for the desired viewport (window size, map center, and zoom level). It may be computationally costly, but it is accurate. Since I've added the USGS topographic data (which is raster elevation data), you can see the graininess of it when you zoom in deeply.

And, alas, vectorization of raster maps is highly error-prone and requires manual corrections.

Andrew Pavlin

Date: Sun, 18 Nov 2012 13:59:03 -0500
From: wa8lmf2 at aol.com
To: aprssig at tapr.org
Subject: Re: [aprssig] Can YAAC or APRSIS32 do a CAVE.JPG map?

    On 11/18/2012 11:29 AM, Robert Bruninga

      Can YAAC or APSIS32 accomodate JPG maps easily?

I need to figure out how to get the Mammoth Cave map into an APRS client.

The map is geographically correct, but I need to register the LAT/LONG
from two corner points and then be able to load it and be able to ZOOM
it during operation.


    1)     Once again,  .JPG is *NOT* the proper format
    for B & W text and non-continuous-tone images like maps, graphs
    & charts, mechanical drawings, schematics, etc.   


    JPG should only be used for continuous-tone real-life
    photos.   The .JPG compression algorithms look for gradual gradients
    between adjacent pixels.   When confronted with abrupt jumps from
    one solid color to another (or from black to white) you only get a
    hideous fuzzy"squirmy" blur at the transition from one solid color
    to another, if any worthwhile amount of compression is being


    The proper lossless formats for images with abrupt transitions
    between solid colors are .GIF, .BMP .PNG or .TIF.  For images with a
    limited number of solid colors (256, 128, 16 or fewer colors) like
    maps, almost always .GIF will yield the smallest file. 



    2)     No  bitmap format like .JPG, .BMP, .GIF, etc that is a fixed
    grid of pixels is going to yield any more detail by zooming in.  You
    just get big chunky blocks as the individual pixels are enlarged.   
    For usable  zooming, you have to use vector formats such as .WMF,
    .SVG, .DXF,  .DWG (AutoCad), .AI (Adobe Illustrator), .SHP
    (ArcView), etc.    



    3)    Uiview has a very straight-forward calibration routine that
    accepts any bitmap in .JPG, .BMP, .PNG, or .GIF format.  Just
    drag-and-drop any such image from the Windows File Explorer into the
    open UIview main window.  A calibration dialog automatically  pops
    up that allows you to either specify the lat/long of the upper-left
    and lower-right corners --OR-- you can click on any two  points with
    known lat/longs (typically things like highway junctions,
    recognizable structures in aerial photos, etc) in the image and
    specify their lat/longs instead.   


    UIview can accommodate bitmap images far larger than it's display
    window.  Instead of downsizing the image to fit with the resulting
    loss of detail, the UIview window becomes a scrollable viewport
    showing a part of the image at full native resolution instead. 


    With the Precision Mapping 9.0 server add-on and Precision Mapping
    9.0 installed, you can either slip a calibrated bitmap underneath
    the transparent vector layers displayed in Uiview.  Or actually use
    it to display your own fully-zoomable home-made vector images in
    ArcView .SHP, or MapInfo .MIF format.     


    If the orignal bitmap image of the map in question is reasonably
    clean, the trace utilities included with Corel Draw or Adobe
    Illustrator can "follow the lines" between colors and create a
    vector version of the image. 


    Some details on using the vector capabilities of Precision Mapping
    are here on my website:







    Stephen H. Smith    wa8lmf (at) aol.com 

    Skype:        WA8LMF

    Home Page:          http://wa8lmf.net



    Acer 756 Netbook: Versatile Inexpensive Platform for Ham Apps



    High Quality Calibrated Static Maps for Any APRS App 



     Vista & Win7 Install Issues for UI-View and Precision Mapping



    "APRS 101"  Explanation of APRS Path Selection & Digipeating 






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