Archive for Geomatics

Converting BNA to GPX

There are some ancient BNA files on my hard disc, dating back to 1996. They were generated using some proprietary mapping software called “GoldenSoft Map View”. I used this programme in university while writing my thesis. At home, I used selfmade utilities I had written for my Atari ST.

The plan to convert those BNA files to GPX has been there for ages – even considering a re-write of my personal map viewer for those files in some object orientated language. But now, I encountered ogr2ogr which can do the job:

ogrinfo -ro -al -summary /mnt/BACKUP/D/map/world.bna
INFO: Open of `/mnt/BACKUP/D/map/world.bna’
using driver `BNA’ successful.

Layer name: world_points
Geometry: Point
Feature Count: 175
Extent: (-99.239204, -51.675117) – (178.408966, 64.260612)
Layer SRS WKT:
Primary ID: String (0.0)
Secondary ID: String (0.0)

Layer name: world_polygons
Geometry: Multi Polygon
Feature Count: 418
Extent: (-178.456192, -81.035141) – (190.044510, 83.616669)
Layer SRS WKT:
Primary ID: String (0.0)
Secondary ID: String (0.0)

Layer name: world_lines
Geometry: Line String
Feature Count: 3
Extent: (-180.010941, -85.472992) – (179.763107, 55.058968)
Layer SRS WKT:
Primary ID: String (0.0)
Secondary ID: String (0.0)

Looks nice, now give it a try:

ogr2ogr -f “GPX” /tmp/world-bna.gpx /mnt/BACKUP/D/map/world.bna
ERROR 6: Field of name ‘Primary ID’ is not supported in GPX schema. Use GPX_USE_EXTENSIONS creation option to allow use of the element.
ERROR 6: Field of name ‘Secondary ID’ is not supported in GPX schema. Use GPX_USE_EXTENSIONS creation option to allow use of the
ERROR 6: Geometry type of `Multi Polygon’ not supported in GPX.

ERROR 1: Terminating translation prematurely after failed
translation of layer world_polygons

Well, there is still some work left. But we are very close…

After all, it is possible to convert BNA to KML or ESRI.

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Open Streetmapping with Motorola A780: Strange values

For some weeks now, I am a proud owner of a linux driven A780 GPS mobile. It is quite easy to open GPS tracks in any text editor: Mounting my Motorola as mass storage is done automagically by udev + hal daemons.

Parsing its contents is less easy – at least if you want to make use of all information stored.
Obviously, tracking is vector orientated: Each vector (logged as one line) has got one start and one end time, latitude, and longitude. In hardly any case, subsequent vectors have common end/start values.

It shouldn’t be very hard to write a parser extracting all given coordinates (i.e. start and end coords for any vector line) – but guessing the meaning of the left columns occurs to be hard:

StDate     StTime   EndDate    EndTime       StLat     EndLat      StLong     EndLong Fix Total     Total #OfObs
(UTC)      (UTC)    (UTC)      (UTC)                                                      Miles     Hours
08/23/2008 09:11:15 08/23/2008 09:15:50  52.029861  52.039635    8.555399    8.598636 1 -3649860701231198131961668199318255273253704759060934360615150772018946839312983390068665767128059356237740002978924188506914396338678317267284591053595745998525189226233856.00     0.000 768152
08/23/2008 09:15:53 08/23/2008 09:17:04  52.039892  52.037446    8.599602    8.614022 1 -78118279941557931703363451455652206793696749610332198789022918111496705774753948327901293097707913114779364083391770081968424685419280192230328808432059202942449336286932111339638257750450957502640494359747686692974231552.00     0.000 768152
08/23/2008 09:17:09 08/23/2008 09:17:28  52.037435  52.037543    8.613871    8.613807 1   -0.00     0.000 768152
08/23/2008 09:17:46 08/23/2008 09:18:12  52.037328  52.039549    8.614043    8.617584 1   -0.00     0.000 768152
08/23/2008 09:18:15 08/23/2008 09:19:43  52.040010  52.047724    8.618184    8.635565 1 -344646659481965599028466738922047546765953134524746744268617381020796015676674827437106811168638611102639620443121993900825615697463858624748128071954920622070466913444633264051453952.00     0.000 768152
08/23/2008 09:19:46 08/23/2008 09:25:32  52.048389  52.066178    8.635329    8.662022 1 -438278375512559217652056156777336964928373076093870088506703880101717226850843193135491371767624957503494869835647695687123337567729156216808571666432.00     0.000 768152
08/23/2008 09:25:36 08/23/2008 09:28:46  52.067304  52.101261    8.662473    8.718177 1 30068130744005489155484081831838965166576489273498100822888867340749494086281791865200369474663529612734774394515077434054123978752.00     0.000 768152

Take note of the huge values shown in the “Total Miles” field – if these are decimal numbers, they would be really big numbers; Calc reads the last column like this:


And what does the last field mean, cryptically named #OfObs ?

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Geomatikprojekt mit Schülergruppen

Was für Wissbegierige die Wikipedia ist, ist das Projekt OpenStreetMap für alle Reisenden, Geographen und Navigatoren. Hier strickt die Weltgemeinschaft fortschrittlicher Internetnutzer/innen an einem globalen Kartennetz, das von Anfang an Gemeingut sein soll.

openstreetmap logo Außer einem Internetzugang benötigen interessierte Beitragsleister (potenzielle Kontributoren) entweder fundierte Ortskenntnis von unbeschrifteten Kartenbereichen – oder ein GPS-Gerät, mit dem sie weiße Flecken auf der Weltkarte vermessen können.

In der letzten Septemberwoche planen wir im Informatikunterricht ein Geomatik-Projekt, für das uns Sponsoren von 10 GPS-Tracker zur Verfügung stellen.

Dafür gilt bereits jetzt mein Dank u.a. an die Geofabrik in Karlsruhe, die die Buchung und den Versand dieser Geräte übernommen hat.


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