aprs is a registered trademark bob bruninga, wb4apr copyright © 2003 – john beadles, n5oom all...

APRS is a registered trademark Bob Bruninga, WB4APR

Copyright © 2003 – John Beadles, N5OOMAll Rights Reserved

Digital Map Data for APRS

John Beadles, N5OOM



Purpose of this Presentation

• This presentation is an introduction to the topic of digital map data

• This is not a how-to

• The topic is too big to be contained in a 1 hour presentation

• But hopefully this will get you started!



Types of Digital Maps

• Feature maps

– Roads, political boundaries, utilities, hydrology, digital elevations, etc.

– Constructed from ground surveys, aerial and satellite photos

– Often one feature type per map data file (or “layer”)

• Geoid Models

– Gravitational field map, used for high precision surveying, etc.

– Constructed by using aerial, satellite gravity surveys

• Digital Elevation Models

– Model of the shape of the earth

– Used for RF propagation modelling, construction estimation, flood plain modelling

– Constructed by ground surveys, stereo aerial photo digitization, SARsat mapping



Geoid Maps



Digital Elevation Map



Vector Map Characteristics

• Raw data consists of points and lines.

• Maps are dynamically drawn, with lines being defined as a series of coordinate pairs

• Maps with unformatted text can be pretty ugly

• Map features can be dynamically edited

• Sometimes used with associated database entries (Geographic Information Systems)

• Includes Tiger data, USGS DLG data used with some APRS software

BEGIN LINE

32.744033,-96.894967

32.744033,-96.894833

32.743967,-96.894767

32.743933,-96.894767

32.743883,-96.894767

32.743817,-96.894767

32.743700,-96.894700

32.743567,-96.894617

32.743417,-96.894567

32.743250,-96.894517

32.743100,-96.894483

32.743000,-96.894417

32.742983,-96.894300

END



• Is basically a picture

• Accompanied with a file containing associated geographic information

• Features are drawn on and cannot be easily modified

• Often used as a base map on which other features are drawn

• .GIFs, .JPGs, GeoTiffs

• Is the default map type used by UI-View, can be used with Xastir, WinAPRS

096.47.216W,34.05.628N

096.46.154W,34.04.781N

2003 MS-150 Sun Lunch Stop

Raster Map Characteristics



Raster Map Examples



Map Data Production – Raw Data

• Collection from raw sources

– Land surveys

– Data collection

– Aerial Photos

– Satellite Photos



Map Data Production – Editing

• Data Production

– Digitization

– Hand entry from notes

– Data addition

– Example: Adding street names and address ranges to a road polyline

– Coordinate conversion & projection

– Depends on the application

– Verification & cleanup



Production Issues

• Scale

• Type of features

• Associating external data

• Datum & Projection

• Accuracy

• Honesty

• Map data production is partly manual, partly automated process

• External data can include items such as street numbers, road classifications, population counts, etc.

• All data is not accurate, and is not necessarily caught in editing

• The production crew can sometimes sneak extra features into a data set. I have seen the name “Bob” added into a Florida data set, laid out in map features.



Erroneous Map Data

• All map data is not necessarily accurate, as is shown by this residential suburb when GPS data is laid on top of it.

• Could have come from incomplete, drawn in planning maps or could have happened by an improper geographic coordinate conversion



Map Data Creators & Suppliers

• State and Local Governments

– City engineering departments

– Local coalitions (NTCOG)

– State environmental agencies

• Federal Government

– U. S. Census Department

– U.S. Geographic Survey

– NIMA (National Imagery & Mapping Agency)

– NASA (Landsat)

• Industrial

– Engineering svc vendors

– Aerial & satellite survey vendors

– Utilities

• Consumer Software Suppliers

– Delorme

– Rand McNally

– Mapsco

• Research institutions



Uses of Digital Map Data

• Government Uses

– Tracking census takers

– Navigation

– Warfighting

– Resource Management

– Environmental Hazard Tracking

– E911

– Political districting

– Disaster management

– Damage assessment

– Weather!

• Industrial Uses

– Fleet tracking

– Utility asset location

– Package delivery

– Construction industry

• Scientific Uses

– Earthquake tracking

– Continental drift

– Tracking biological diversity

• And many more!!!



Map products useable for APRS



Vector Data

• Census Dept TIGER Data

– Xastir

• USGS Digital Line Graphs

• WinAPRS / MacAPRS file format

– WinAPRS / MacAPRS

– UI-View

– Xastir

• PocketAPRS file format

• Commercial Data

– Used in MapInfo, AutoCad

– Would need to be converted to proper format

• Tiger data is complete, but quality can be highly variable but is updated regularly

• USGS DLG (Digital Line Graphs) are digitized versions of USGS 1:24000 maps, rarely updated

• Commercial data is often Tiger data that is formatted and cleaned up – very expensive!

• Some conversion software exists to convert TIGER, DLG data to WinAPRS / MacAPRS format



Consumer Software Products

• Delorme StreetAtlas

– APRS+SA

– UI-View (some versions of SA)

• Precision Mapping

– UI-View

– WinAPRS

• Microsoft MapPoint

– APRSPoint

• Generally APRS software that uses a consumer product doesn’t directly access the data directly, it uses a programming interface to talk to the mapping software, which does what the APRS software wants it to do

• Therefore, the APRS program is dependent on the programming interfaces provided by the map software. Not all map software provides this interface.

• Map data used in consumer map products is virtually always proprietary – you aren’t allowed to access or convert the raw data.

• Most of these products are based on updated TIGER data from the US Census Dept.



Web Based Products

• Tiger Map Server

• MapBlast

– JavAPRS

– Radio Mobile

• TerraServer

– UI-Terra

– Xastir

• Used to create a raster map which you can then take with you

• Can’t make new maps unless you are connected to the internet

• UI-Terra is downloadable from the UI-View web site

• Radio Mobile is an RF Propagation package that can be used to make APRS (UI-View) compatible raster maps



Maps generated from RadioMobile



Scanned & Raster Maps

• GeoTIFFs

– Various sources

– WinAPRS / MacAPRS

– Xastir

• Digital Raster Graphics

• UI-View map format

– Graphic image & geoinfo file

• GeoTiffs are a specific image format that has associated geographic information associated with it

• Digital Raster Graphics are scanned copies of USGS 1:24000 maps

• UI-View format is a .bmp or .jpg with an associated text file containing the lats and longs of the upper left and lower right corners.



Photos generated with UI-Terra

096.47.216W,34.05.628N

096.46.154W,34.04.781N

2003 MS-150 Sun Lunch Stop

UI-Terra builds an area photo by downloading photo tiles from TerraServer and generates a text .inf file containing the upper left and lower right coordinates of the image.



GIS Data

• Arcinfo Shape Files

– Xastir

• MapInfo

– Useable only after conversion

• GIS data is generally vector data that is formatted for a particular industrial GIS application

• ArcInfo shape files are useable by some applications

• Need to check copyright information on the source data.



Do It Yourself Data

• May be needed to correct bad map data

• Collect with GPS

– Use within a mapping program (such as a “draw layer” in StreetAtlas

– Or save as a text file and compile into a vector format useable directly by a program

• Hand drawn

– Street Atlas provides a function for drawing roads in by map



Resources

• US Census Dept

– http://www.census.gov

• US Geological Survey

– http://geography.usgs.gov

• National Geodetic Survey

– http://www.ngs.noaa.gov

• Navtech Seminars

– http://www.navtechgps.com

• National Imagery and Mapping Agency

– http://www.nima.mil

• Radio Mobile

– http://www.cplus.org/rmw/english1.html

• UI-View Map tools

– http://www.ui-view.com/uiview32/mapsoftware.shtml

Useful books from Navtech Seminars:

“Glossary of Mapping, Charting and Geodetic Terms”

Defense Mapping Agency

“Geodetic Glossary”

National Geodetic Survey, Rockville, MD

“NOAA Professional Paper NOS 2, North American Datum of 1983”

National Geodetic Survey, Rockville, MD

“Map Projections – A Working Manual”

U. S. Geological Survey professional paper; 1395

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