Presentation notes used to introduce WebGIS building process to a non-programmers audience.

1. Notes from
a WebGIS
implementation
(for non-programmers and desktop GIS users)
Paolo Verri <paolo.verri@gmail.com>

2. From
Desktop GIS
to
WebGIS:
architecture

3. Desktop GIS
Architecture
Local GIS
Program
Local Data
(everything is near you, on your PC)

4. Web GIS Architecture
Browser Web Local GIS
GIS Client Client
Network
Remote Data
MapServer
(GIS Database)

5. Build a WebGIS:
4
main activities

6. 1
WebGIS
architecture setup
! IT skills

7. 2
data production &
manipulation
! Geo & SQL skills, data
structure design is critical

8. 3
web map configuration &
styling
!! Geo skills, styling can be time-
consuming

9. 4
map-user interaction
!!! IT & Geo skills,
lots of javascript programming,
time-consuming

10. From
Geodatabases
to
PostGIS
(Vector data)

11. Shapefiles,
Geodatabase
DBF files
1

12. Shapefiles,
SQL files
DBF files
2
shp2pgsql myshapefile.shp myschema.mytable > mytable.sql
!
SRID
Input encoding
Identifier’s case

13. SQL files PostGIS
3
pgsql mytable.sql
!
Database configuration
Output encoding
Dataset size

14. From
PostGIS
to
Web Maps
(with MapServer)

15. Web Map
?
Image, representing geographic
information, with an internet
address (URL),
displayed in a web browser

16. Image Address (URL)
Map
Web Browser

17. MapServer
?
Receives browser requests, queries
PostGIS database, produces images,
sends them back to browser

18. Publishing Web Maps
=
Tell MapServer how to build
images out of geographic data when
requested by web browsers.

19. How to tell MapServer: configuration example.
Web Map Name
Geographic Extent and
Geometry Type
PostGIS connection
Styling

20. From
Web Maps
to
Web GIS
(interacting with maps)

21. geographic data storage,
calculations and maps production
happen far far away.
map interaction
happens near you
(yes, in your browser, thanks to javascript)

22. Basic Web Map Interaction
(read only)
=
Pan
Zoom
Layers switch
=
Openlayers javascript library

23. Complex Web Map Interaction
(read, write)
=
Query features infos
Select features
Calculations (distance, area...)
Input data forms
=
GeoExt javascript library

24. Tools of the trade

25. Store and organize the data
Postgres (SQL database)
+
PostGIS (geo extensions and utilities)
+
pgAdmin (GUI, database front end)
(but there’s a command line too)
http://postgis.refractions.net/

26. Manipulate the data
GDAL (raster geospatial data formats)
+
OGR (vector geospatial data formats)
(ESRI shapefiles!)
+
PROJ.4 (cartographic projections)
Packages found at: http://www.maptools.org/

27. Generate and Publish Maps
Mapserver (generate maps and more...)
+
PHP/Mapscript (programming language,
for dynamic map generation)
(it happens server side!)
+
Web Server (send maps to the browser)
(and HTML pages too)
Packages found at: http://www.maptools.org/

28. Manage User Interaction
javascript
+
Openlayers (maps in html pages)
+
ExtJS (javascript library, complex GUIs)
http://www.geoext.org/