NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.
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Transcript of NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.
![Page 1: NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.](https://reader035.fdocuments.in/reader035/viewer/2022062516/56649d375503460f94a0fd83/html5/thumbnails/1.jpg)
NR 322: Editing Spatial Data
Jim Graham
Fall 2008
Chapter 6
![Page 2: NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.](https://reader035.fdocuments.in/reader035/viewer/2022062516/56649d375503460f94a0fd83/html5/thumbnails/2.jpg)
Digitizing Spatial Data
• We are creating a representation of objects on the earth
• What accuracy is important?
• How did we determine their position?
• How will the data be used?
![Page 3: NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.](https://reader035.fdocuments.in/reader035/viewer/2022062516/56649d375503460f94a0fd83/html5/thumbnails/3.jpg)
Accuracy
• Accuracy: How closely the data matches truth
• What accuracy do we need to maintain?
• Typically you want to collect data that is twice as accurate as will be needed to allow for conversions to decrease the accuracy.
![Page 4: NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.](https://reader035.fdocuments.in/reader035/viewer/2022062516/56649d375503460f94a0fd83/html5/thumbnails/4.jpg)
Data Collection
• How was the data collected?– GPS– Topographic Map– Surveys to benchmarks– “About here” on a satellite photo
• Each step has an effect on accuracy:– Instrument– Digitizing– Transforms (projection)
![Page 5: NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.](https://reader035.fdocuments.in/reader035/viewer/2022062516/56649d375503460f94a0fd83/html5/thumbnails/5.jpg)
How will the data be used?
• Maps at large extents, low resolution?
• Maps at small extents, high resolution?
• Analysis?
![Page 6: NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.](https://reader035.fdocuments.in/reader035/viewer/2022062516/56649d375503460f94a0fd83/html5/thumbnails/6.jpg)
Digitizing Process
• ArcCatalog:– Create the Shapefile
• ArcMap:– Add the Shapefile (or Coverage, or GeoDatabase)– Add attribute fields– Start Edit– Add points, polylines, polygons– Add attribute values– End Edit
• ArcCatalog:– Add Metadata
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Create New Shapefile
• In ArcCatalog:– Select New -> Shapefile– Select the type of file– Define the spatial reference (coordinate
system) to match the raster– Z adds an elevation– Don’t worry about M yet
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Questions to ask before editing
• Points:– What part of the feature to identify?
• Adding Polylines– What level of stream?– What level of road?
• Adding Polygons– What level of resolution?– How small a feature to include?
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Editing Points
• Adding:– Tool: Sketch Tool– Task: “Create New Feature”– Target: Matches Point Layer– Click to add points
• Edit/Delete:– Tool: Edit Tool– Task: NA– Drag to move points– Right-click to delete points
![Page 10: NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.](https://reader035.fdocuments.in/reader035/viewer/2022062516/56649d375503460f94a0fd83/html5/thumbnails/10.jpg)
Editing Polylines
• Adding Polylines:– Set “Snapping”– Tool: Sketch Tool– Task: “Create New Feature”– Click to add points– Double-click to end polyline
• Editing Polylines:– Tool: Edit Tool– Task: Modify Features (watch this)– Drag to move vertices with special cursor– Right-click to delete vertices
![Page 11: NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.](https://reader035.fdocuments.in/reader035/viewer/2022062516/56649d375503460f94a0fd83/html5/thumbnails/11.jpg)
Editing Polygons
• Adding Polygons:– Set “Snapping”– Tool: Sketch Tool– Task: “Create New Feature”– Click to add points– Double-click on start vertex
• Editing Polylines:– Tool: Edit Tool– Task: Modify Features (watch this)– Drag to move vertices with special cursor– Right-click to delete vertices
![Page 12: NR 322: Editing Spatial Data Jim Graham Fall 2008 Chapter 6.](https://reader035.fdocuments.in/reader035/viewer/2022062516/56649d375503460f94a0fd83/html5/thumbnails/12.jpg)
Editing Metadata
• Select the file in ArcCatalog
• Select “Edit metadata”
• Enter all 200 fields!
• Fill out:– Identification: required fields– Data Quality– Spatial Reference– (not required for Lab 7!)