GIS data input. In the early days of GIS 1980s and early 1990s. We used canned datasets for teaching (from USA)

Transcription

1 GIS data input GIS is the automated : acquisition - input management analysis display of spatial data In the early days of GIS 1980s and early 1990s There were no or little GIS data We used canned datasets for teaching (from USA) Some data were unusable due to data formats Some early data were digitised in US Prisons 1

2 Data input and sources GIS and mapping layers: -- Base map data and topography: e.g. lakes, roads, rivers, contours - aerial photos and surveying -- Thematic layers e.g. population density, income, climate - Statistics and censuses, weather stations Mapping from 2

3 Air photos combined with surveying for ground positioning: e.g. triangulation Theodolite Triangulation station Geodetic station PG Map available since 2005: municipal data from various sources PGMAP photo layers every 3 years 3

4 GIS Data Input 1. Digitizing from maps and air photos 2. COordinate GeOmetry (COGO) 3. Keyboard - typing 4. Global Positioning Systems (GPS) 5. Scanning (raster) 6. Satellite images 7. New millennium sources 1. Digitizing Digitizing is done in two ways: a. Tracing lines on maps initially using a tablet with map taped down, or onscreen / heads-up (= copying a map) > 1995 GIS technician jobs 1980s / 90s Digitising from printed maps 4

5 b. Onscreen from digital photography ('first hand data') post 1985 Digitising editing is still needed: updates and errors Locations are based on underlying georeferencing e.g. UTM A line consists of a series of vertices Vertices close to form a polygon (same start/end point) Edits: e.g. adding new features, modifying existing features, creating a new layer ArcEdit: 5

6 2. Co-ordinate geometry (COGO) used for high precision municipal data, based on ground survey of azimuth and distance from known points, rather than a coordinate system.. This is less common in natural resources Keyboard.. primarily for attribute data Attributes can be entered as integer, real (decimal), text or date These may be added at time of digitising e.g. contour lines and elevations Or separately entered into spreadsheet Spatial coordinates are usually collected by the other methods 6

7 4. Global Positioning Systems (GPS) A growing source of data since the 1990s: mostly spatial data e.g. new features such as trails, or cutblocks. Attributes can be added during data collection, or later (by keyboard) Bike trails on Cranbrook Hill between UNBC and Ospika Drive (UNBC GIS project) GPS applications 7

8 GPS wildlife collars locations of one bear -> 8

9 5. Scanning (Raster): creates.jpg /.tif -> geotiff (georeferenced) Scanning (Raster): creates.tif or geotiff (georeferenced) Scanning produces an ungeoreferenced raster map or photo file that can be used as a background layer for digitising It cannot easily recognize lettering, and point symbols This needs raster to vector (R2V) software e.g. ArcScan Raster display of contour lines Selected series of connected cells ArcScan for ArcGIS: 9

10 Digitising over scanned map 1923: Interprovincial (BC-AB) mapping 1923 contours and glacier extents on relief model 10

11 6. Satellite Image processing vectors from digital satellite imagery digital Landsat TM 26 June 2009: completion of Canada s 1:50,000 mapping Sept 2010 Sept

12 6. Satellite Image processing vectors from digital satellite imagery digitise or processed GEOG432: Remote sensing automated processing Glacier change: Nass Icefield

13 Landsat 8, 2015 Glacier change: Nass Icefield Geo-referenced JPG 185 x 185 km Free download and open in arcmap (since ~2010) Fire, 2015 Jasper Park, north of Mt. Robson park Glacier change: Nass Icefield 13

14 7. New data sources post-2000 High resolution satellite images (25cm 1m) Light Detection and Ranging LiDAR Digital aerial photography georeferenced Unmanned Aerial Vehicles (UAVs) 8. Data import sources (Thursday) This is the most common process today due to supply of digital data- previously created by digitising and the other methods The data are stored in standard formats read by GIS software, often shapefiles 14