Spatial Data

Map Projection Transformations functionality concerns the transformation of data in geographic coordinates for an existing map projection to another map projection. Most GIS software requires that data layers must be in the same map projection for analysis. Accordingly, if data is acquired in a different projection than the other data layers it must be transformed. Typically 20 or more different map projections are supported in a GIS software offering.

Interactive graphic editing functions involve the addition, deletion, moving, and changing of the geographic position of features. Editing should be possible at any time. Most graphic editing occurs during the data compilation phase of any project. Remember typically 60 to 70 % of the time required to complete any project involves data compilation. Accordingly, the level of sophistication and ease of use of this capability is vitally important and should be rated highly by those evaluating GIS software. Many of the editing that is undertaken involves the cleaning up of topological errors identified earlier. The capability to snap to existing elements, e.g. nodes and arcs, is critical.

1. Real-world features are selected or not selected for inclusion on a map.

2. The cartographer communicates the spatial pattern and organization of real-world objects on a map.

3. Point, line, and area symbolism is chosen.

4. Misleading or erroneous information is added to a map.

5. Real-world features are simplified to allow them to be drawn on a map at reduced scale.

Real-world features are simplified to allow them to be drawn on a map at reduced scale.

The cartographer communicates the spatial pattern and organization of real-world objects on a map.

Real-world features are selected or not selected for inclusion on a map.

1. Annotation

2. Scale bar or ratio

3. Map features (points, lines, areas, surfaces)

4. Projection information

5. Pictures and anecdotal evidence

Projection information

Annotation

Map features (points, lines, areas, surfaces).

Scale bar or ratio.

1. 500 centimeters

2. 50 centimeters

3. 50 metres

4. 5 metres

50 metres

1. Azimuthal

2. Cylindrical

3. Geographic

4. Conic

Geographic

1. As a collection of points, lines and areas

2. As a collection of points

3. As a single point

4. As an area

5. As a line

As a collection of points, lines and areas

1. Coordinate transformation

2. Buffering

3. Polygon overlay

4. Polygons coordinate thinning

Polygons coordinate thinning