18-Geom-A7 Geospatial Information Systems · May 2014
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2014 — 04-Geom-A7 Geospatial Information Systems. Closed-book; no calculator permitted. Format: twenty-three short-answer questions of equal value (5 marks each); a candidate answers any twenty, but all twenty-three are solved in full below. Datum and coordinate conventions follow the Canadian spatial reference framework — NAD83(CSRS) horizontally and CGVD2013 vertically.
Reference texts: P. A. Longley, M. F. Goodchild, D. J. Maguire & D. W. Rhind, Geographic Information Systems and Science (4th ed., Wiley, 2015); P. Bolstad, GIS Fundamentals: A First Text on Geographic Information Systems (6th ed., XanEdu, 2019); P. A. Burrough, R. A. McDonnell & C. D. Lloyd, Principles of Geographical Information Systems (3rd ed., Oxford, 2015); M. Worboys & M. Duckham, GIS: A Computing Perspective (2nd ed., CRC, 2004); ISO 19115 Geographic information — Metadata.
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
Spatial data (also called geometric or locational data) describes where a feature is and its shape — its position, geometry and, in a topological model, its connectivity relationships with neighbouring features. It is recorded as coordinate pairs organized into geometric primitives: points, lines (arcs) and polygons in the vector model, or as an array of georeferenced cells in the raster model. Attribute data (also called thematic, descriptive or non-spatial data) describes what a feature is — the properties or characteristics of each spatial feature — and is stored as records in tables, one row per feature and one column per attribute. The two are joined by a common feature identifier so that a geometry and its descriptive record behave as a single object. Examples of spatial data: the coordinate string defining a parcel boundary, a road centreline, a survey monument point, or a lake polygon. Examples of attribute data: the parcel's PID, owner, zoning and assessed value; the road's name, surface type and speed limit; the monument's elevation and order; the lake's name and water quality class. Spatial data positions the feature; attribute data gives it meaning.
