GPS-i Paq Workshop by Kees de Bie NRS

GPS-i. Paq Workshop by Kees de Bie NRS / ITC Version Oct’ 02 Mobile GIS techniques with 10 m accuracy !!

GPS-i. Paq Hardware Parts

Some relevant info … Pocket PC The Compaq-i. PAQ pocket PC (64 MB Ram), running at > 200 Mhz under MS-Windows. CE) is able to run Arc. Pad and to connect to a GPS. The Pocket PC has backlight-features so that in bright sun the screen is still perfectly readable. Arc-Pad is able to convert GPS readings ‘on-the-fly’ to the required coordinate system. Any image, GT-Sheet, or shapefile can be displayed in Arc-Pad ‘as is’. The GPS position is shown on the loaded maps or images. The user can save the GPS-Tracklog (as lat-long points), or use the GPS to capture shapefiles (point, line, or polygon) in the required projection system. The software allows use of forms (questionnaires), and to draw points, lines, or polygons directly by hand on the screen. Raster images must be converted to SID files using Erdas (v. 8. 5). Arc-Pad software comes with an extension that loads into Arc-View or Arc-Map.

Example-1 … Pakistan Arc. Pad Menu Scanned topsheet Peshawar City Part of GT-Sheet Digitized “on the road” Forest. GIS Office Digitized line of GT-Road and Circular-Road DHV guesthouse Points of Interest 1038 m 2 1881 m 2 2 Fields: RMS boundary Scale: 1: 65540

Example-2 … India IRS-Image (23 m Multispectral fused with 6 m Pan) Sep. 2002 Digitized “in the field” Jan. 2000 Sep. 2002

Example-3 … Iran Aster-Image, Topsheet, GPS data… All fit !!! Aster-Image (15 m Multi-spectral) Jul. 2001 Digitized “in the field” and “on the road”

Connecting Hardware-1 Power USB hub

Connecting Hardware-2 GPS physical connection A GPS serial connector wire needs to be linked to a serial connector wire attached to the i. Paq. Both ends are female and need to be connected through a null-modem connector in which pins 2 and 3 are reversed (welded by me…).

Connecting Hardware-2 Connection precaution While cycling, walking or running, the connections must remain firmly in place. Use tape to provide the required solid ‘fix’.

Connecting Hardware-2 Watch your battery life On the road, a cigarette-lighter wire provides recharge options for the i. Paq. Use rechargeable A 4 batteries for the GPS. Carry spares with you at all times. Power

Software installation-1 • Activesync use your CD will establish the required ‘communication’ USB hub

Software installation-2 • Arcpad on your PC run:

Software installation-3 • Arcpad from your PC to your i. Paq install from [Start] - [Arc. Pad] • Try-out files for Enschede: copy : …. Arc. Pad_Enschede*. * to your PC and your i. Paq USB hub

Hardware settings: GPS settings • units’ settings: position format: hddd. dddddo, map datum: WGS 84, and units: metric • ‘interface’ settings: i/o format: NMEA out, and baud rate: 4800.

Hardware settings: Arc. Pad Arc-Pad settings • GPS: NMEA protocal, WGS 84 Datum • GPS Port: port com 1, Baud 4800, Parity none, Data bits 8, Stop bits 1, Break 0.

Projection settings-1 To convert ‘on-the-fly’ coordinates send by the GPS to Arc-Pad, at least one Arc-View shapefile must be loaded as Arc-Pad layer for which a projection file (*. prj) exists in the same directory as from where the shapefile was loaded. Example “Enschede” : PROJCS["ED_1950_UTM_Zone_32 N", GEOG CS["GCS_European_1950", DATUM["D_Euro pean_1950", SPHEROID["International_1924", 6378388, 297]], PRIMEM["Greenwich", 0], UNIT[ "Degree", 0. 0174532925199433]], PROJECTI ON["Transverse_Mercator"], PARAMETER["F alse_Easting", 500000], PARAMETER["False_ Northing", 0], PARAMETER["Central_Meridian", 9], PARAMETER["Scale_Factor", 0. 9996], PAR AMETER["Latitude_Of_Origin", 0], UNIT["Meter ", 1]]

Projection settings-2 Then, when applicable, the correct datum shift must be selected within Arc. Pad. Example “Enschede” :

Prepare projection file-1 Select in Arc. View a shapefile and start the “Arc. View Projection Utility”. Arc. Pad 6 supported projections: • Geodetic coords. (Lat-Long) • Alberts Equal Area Conic • Cylindrical Equal Area • (Double) Stereographic • UTM (TM; Gauss-Kruger) • Lambert Conformal Conic • New Zeeland National Grid

The next ILWIS release can make file-2 Alternative option to make a *. prj file Prepare projection *. prj files Start in Arc. Map the “Arc. Pad Tools” wizard and export a *. SID image.

Compress Images can be compressed by a factor 25!!! No need is left to prepare clumsy JPG's for Arc. Pad. Mr. SID images will do!! They hardly suffer from resolution loss when compressed, and can cover substantial areas ( the original IMG file must be < 50 MB). Example: an AP from Enschede is compressed from 25 to 1 MB. Shown is a fraction of the original image!! SID IMG

Mapping in the Field-1 Performance in Hills Often, main roads are poorly mapped on GTsheets, while (15 m resolution) images of mountainous areas hardly show the roads. Digitizing roads by GPS in hills proved very useful and accurate enough to fill this shortcoming. Digitizing administrative boundaries in hills on foot using a GPS is not considered practical. Roads digitized in Ghazi RMS on top of a GT sheet and on an Aster image (Febr. 2001; scale 1: 25, 000).

Mapping in the Field-2 Performance under trees Cycling to work during a cloudy morning provided the yellow line. It is projected on AP’s, an Ikonos image and the Top -10 of Enschede. Where high trees were present, tracking with the GPS give visible errors. Arc. Pad can provide accuracy warnings !!!

Mapping in the Field-3 Use of GPS to check Image Geo-Referencing quality Outdated GT-Sheets can create problems while georeferencing images. Through the GPS-Ipaq set, digitized roads can be used to check if images are properly geo-referenced. The geo-referencing of the Aster image (Febr. ’ 01) is clearly not matching required standards. Part of an old GT sheet and the new feeder canal under construction at Tarbela on a recent Aster image (Febr. 2001); scale 1: 25000.

GPS-i. Paq Warnings The Arc. Pad manual is only 390 pages thick !!! • Not for GIS amateurs • Requires user to know facts on projection systems ‘properly’ • Requires proper preparation: Once all is done well…. experience shows too many advantages and even a dependancy of using the equipment during fieldwork !!! • of geo-referencing images • of compressing images • of converting shapefiles • of preparing symbologies • of preparing forms • Requires proper GPS-Arc. Pad software settings Time for an inhouse demo of ‘bells-andbuttons’

Try-out files for Enschede