teaching with maps teaching and learning soil science with maps in the field –began in 2005...

Teaching With Maps• Teaching and learning

soil science with maps in the field– began in 2005

• Students study maps while in the field and learn how to connect the geomorphic features and soil properties they see on the maps with the real features in the field.– learn how to “read a

landscape”

Teaching With Maps

• Dataset includes all of Indiana– soil properties– topography– land use– bedrock geology– historic maps

On the Webhttp://isee.purdue.edu

A Lot of Detail• SSURGO Soils Dataset

– 100+ years of soil survey – originally mapped at 1:20,000 or

better– 1.3 million polygons, smallest ~2

acres– 3.5 to 4.0 million ground truthed

observations• 2005 Indiana Map Digital

Elevation Model– resampled to 5 meter resolution

Large Data Sets, Large MapsCell Size(meters)

Pixels Uncompressed Sizeup to

Map Size(@264 pixels / in.)*

640 x 640 456 x 696 310 KB 2 x 4 in

320 x 320 912 x 1,391 4.8 MB 3 x 5 in

160 x 160 1,824 x 2,782 19 MB 7 x 11 in

80 x 80 3,648 x 5,564 77 MB 14 x 21 in

40 x 40 7,298 x 11, 128 306 MB 2 x 4 ft

20 x 20 14,591 x 22,255 1.2 GB 5 x 7 ft

10 x 10 29,181 x 44,510 4.8 GB 9 x 14 ft

5 x 5 M 58,362 x 89,020 19.1 GB 18 x 28 ft

* Resolution of Apple iPad (3rd generation)

The Challenge• Move the maps in Isee from ArcGIS running on

rugged tablet PCs to an app running on the iPad.– iPad is lighter, longer battery life, no startup time, easier

maintenance

Requirements for iPad App

• Must be able to download the full maps(no need for map server)– grab iPad and take it anywhere

• GPS input to determine location• Easy to zoom and pan

Candidate iPad Apps

• ArcGIS– requires connection to map server

• iGIS for iPad– requires maps in Google Maps format

• thousands of individual files and subdirectories – GPS input

• MapBox– requires maps in MBTiles format– no GPS input at this time

TileMill

• Open source map creation program– Mac, Ubuntu Linux, and Windows– raster data as GeoTIFs in Web Mercator projection

• Tiles the map to the MBTiles format– each map stored in a SQLite database as a single file– Maps can be hosted online

• by MapBox• on own server using TileStream

– Maps can be easily downloaded to the iPad and viewed in MapBox