2. Copyright © 2006 Bruce Kessler All Rights Reserved Ch. 2 Data Issues Juggling with both hands (life is much easier)

3. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-2 Goals Better management of ArcView and ArcView Projects Managing –Shapefiles –Coverages Projections –Definition –Conversion between Using GPS data as event themes Work with tables

4. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-3 The Project File Stores objects and their definitions Data “Sources” are stored with full path name. By default, the path to objects is hard-coded

5. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-4 This Can Lead To The Dreaded “Where Is?” Project repair

6. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-5 Create an Indestructible Project Methods –Edit.apr file –Use relative paths –Use environment variables Platform independence

7. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-6 Edit the.apr File Use any text editor Update pathnames Save as text file (no formatting) in a new file Do not edit other object definitions Replace c:\kesslergis\arcviewidl\data\streams.shp With d:\kesslergis\arcviewidl\data\streams.shp

8. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-7 Use Relative Pathnames Data in directory below project Forward slash (/) is platform independent OR C: ArcViewIDL Ex2.apr Data Streams.shp Streams.dbf Streams.shx /arcviewidl projects Ex2.apr data streams.shp streams.dbf streams.shx

9. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-8 Set and Use Environment Variables What are they? –Define working environment –Set to data location Why use them? –Simplify data access –Platform / machine independence How to set them –Use System Properties

10. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-9 Geographic Coordinates Start with a sphere attempting to describe the shape of the earth (GRS 1980) Datum –The position of the sphere relative to the center of the earth i.e. NAD83 & WGS84

11. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-10 Geographic Coordinate System Angular measurement based on the sphere –Longitude –Latitude Measurement is difficult in degrees –I.e. How large is 1 degree square? ESRI 2000

12. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-11 Projections A formula that transforms feature locations between the earth's curved surface and a map's 2 dimensional surface. A projected coordinate system includes the information needed to transform locations expressed as latitude and longitude values to x,y coordinates on a planer system. X Y ESRI 2000

13. Copyright © 2006 Bruce Kessler All Rights Reserved Intermediate ArcView for IDL 2-12 Exercise Data Issues Managing ArcView Managing Projects Managing Shapefiles / Coverages Projections GPS Data Tables