A Gentle Introduction to GIS (PyCon 2012)

I gave a talk at PyCon! These are the slides! Hello!

Transcript

1. PYCON 2012 A GENTLE INTRODUCTION TO GIS Jason Scheirer esri bit.ly/pycongis
2. Front Matter Things I wish I’d known Lots of theory The web is already covered bit.ly/pycongis
3. More than points
4. More than points
5. More than points
6. More than points
7. More than points
8. More than points
10. Storage
11. Vector Data FILE Shapefile KML GML GPX GeoJSON Spatialite File GDB (Esri) DATABASE SQL Server Oracle PostGIS
12. Raster Data FILE GeoTIFF JPEG2000 Esri GRID NetCDF HDF5 IMG ECW MrSID File GDB (Esri) DATABASE SQL Server Oracle PostGIS
13. Data is conventional
14. Constraints are not Integrity = Topology
15. COPY/CONVERT/TRANSLATE/REPROJECT ogr, pyproj ogr2ogr, gdalwarp, gdaltransform, gdal* arcpy.management.CopyFeatures arcpy.management.CopyRaster arcpy.management.Project arcpy.management.DefineProjection OSS: ArcGIS:
16. What
17. Perfect sphere
18. Lumps and bumps
19. Tweak to fit
20. Just a little more...
21. Close enough!
23. Geodesy
24. WGS 84 Global Positioning System datum
25. NAD 83 North American datum
30. DEGREE/MINUTE/SECOND 17°39'27"E 14°42'33"N DECIMAL DEGREES 17.6574318720082 14.7092630700184 UTM ZONE 33P 1627845N 786174E
31. UTM ZONES
32. UTM GRID
33. UTM GRID
34. U.S. STATE PLANE !
37. Geographic Coordinate Systems Global Degrees Regional UTM Zones Local Grids/Planes
38. Visualization
40. f(x, y, z) (x, y) Map Projection
41. Mathematical model of planet/area of interest Datum/Grid/Benchmark Context for referring to places on model Geographic Coordinate System Mapping from geographic to map coordinates Projected Coordinate System Map
42. The big tradeoff Preservation of shape Preservation of area
43. Every map is a LIAR
54. Great Circle
55. >>> geod = pyproj.Geod(ellps='WGS84') >>> geod.npts(-116.993, 36.404, -0.659, 53.501, 10) [(-111.95067424159357, 41.97895680147041), (-105.96857250647616, 47.28567205186159), (-98.70968905555657, 52.20795019303087), (-89.76321873473009, 56.57373830261407), (-78.73417693105489, 60.137140502912196), (-65.50792704328728, 62.583294153845756), (-50.664741106486275, 63.59986753968315), (-35.59231296246254, 63.024821865584016), (-21.813955926298505, 60.952490703845044), (-10.156489980662073, 57.66944410754948)]
56. >>> sr = arcpy.SpatialReference("WGS 1984 World Mercator") >>> start, end = (arcpy.Point(-116.993, 36.404), arcpy.Point(-0.659, 53.501)) >>> polyline = arcpy.Polyline(arcpy.Array([start, end]), sr) >>> [polyline.positionAlongLine(polyline.length * (idx / (11.))) for idx in xrange(12)] [<PointGeometry object at 0x2cca5e10[0x45ff6fe0]>, <PointGeometry object at 0x2cca5e90[0x2cca55e0]>, <PointGeometry object at 0x2cca5f10[0x2cca5da0]>, <PointGeometry object at 0x2cca5f30[0x2cca5ec0]>, <PointGeometry object at 0x2cca5f50[0x2cca5f60]>, <PointGeometry object at 0x2cca5f90[0x2cca5fa0]>, <PointGeometry object at 0x2cca5fd0[0x2cca5fe0]>, <PointGeometry object at 0x2cca5a90[0x2cca5ac0]>, <PointGeometry object at 0x2cca5610[0x2cca5a40]>, <PointGeometry object at 0x2cca5b90[0x2cca5b00]>, <PointGeometry object at 0x2cca40b0[0x2cca40c0]>, <PointGeometry object at 0x2cca40f0[0x2cca4100]>]
59. Analysis
60. Doing stuff with spatial data
61. Geocoding 480 New York St, Redlands, CA Art Galleries near 92373 White House
62. Network Analysis Right on... Left on... Currently there are 15 households without power...
63. Spatial Analysis Relational Topological
64. Relational operators Contains Indicates if this geometry contains the other geometry. Crosses Indicates if the two geometries intersect in a geometry of lesser dimension. Disjoint Indicates if the two geometries share no points in common. Negate this result to compute the Intersect relation. Equals Indicates if the two geometries are of the same type and define the same set of points in the plane. Overlaps Indicates if the intersection of the two geometries has the same dimension as one of the input geometries. Touches Indicates if the boundaries of the geometries intersect. Within Indicates if this geometry is contained (is within) another geometry.
65. Relational operators NOT DISJOINT
66. Topological operators Boundary The boundary of this geometry. A polygon's boundary is a polyline. A polyline's boundary is a multipoint. A point or multipoint's boundary is an empty point or multipoint. Buffer Constructs a polygon that is the locus of points at a distance less than or equal to a specified distance from this geometry. Convex Hull Constructs the convex hull of this geometry. Cut Splits this geometry into a part left of the cutting polyline, and a part right of it. Difference Constructs the geometry containing points from this geometry but not the other geometry. Intersect Constructs the geometry that is the set-theoretic intersection of the input geometries. Use different resultDimension values to generate results of different dimensions. Symmetric Difference Constructs the geometry that contains points from either but not both input geometries. Union Constructs the geometry that is the set-theoretic union of the input geometries.
67. Topological operators
68. Topological operators
69. Topological operators
70. Topological operators
71. Topological operators
72. Topological operators
73. Topological operators
74. Intersect/not disjoint (ArcGIS) sr = arcpy.SpatialReference("WGS 1984 World Mercator") with arcpy.da.SearchCursor('fastfood.shp', 'SHAPE@' spatial_reference=sr) as cursor: buffered_points = [row[0].buffer(1000) for row in cursor] with arcpy.da.SearchCursor('schools.shp', ['SHAPE@', 'school_name']) as school_cursor: schools_within_1k_of_fast_food = [row[1] for row in school_cursor if any(not shape.disjoint(pt) for pt in buffered_points)] buffer_dataset = arcpy.analysis.Buffer('fastfood.shp', r'in_memory\buffered_points', '1 kilometer') arcpy.analysis.SelectByLocation('schools.shp', 'within', buffer_dataset) arcpy.management.CopyFeatures('schools.shp', 'found_schools.shp') arcpy.management.Delete(buffer_dataset)
77. gis.stackexchange.com bit.ly/pycongis Basemaps used: Light Gray Canvas, World Topo, National Geographic World Map. All on ArcGIS Online.