GIS Web GIS and Services 5

Question 1

What is the difference between WMS and WMTS in terms of how they serve map images?

Accepted Answer

WMS renders maps dynamically per request; WMTS serves pre-generated cached tiles

Answer

WMS generates a custom map image for each request, while WMTS serves pre-cached tiles from a fixed tile matrix, providing much better scalability for high-traffic scenarios.

Question 2

In a Web GIS application, what does 'spatial filtering' in a WFS request allow you to do?

Accepted Answer

Request only features that meet a geographic criterion (e.g., within a polygon)

Answer

Spatial filters in WFS (e.g., BBOX, Within, Intersects) restrict returned features to those satisfying a geographic predicate, reducing data transfer.

Question 3

Which format does the OGC 3D Tiles specification use to stream massive 3D geospatial datasets (e.g., city models) to a web browser?

Accepted Answer

Hierarchical tiled batched 3D model (b3dm) and tileset.json

Answer

3D Tiles uses a tileset.json hierarchy with tile formats like b3dm (Batched 3D Model) to stream large 3D city models to clients such as CesiumJS.

Question 4

What is the purpose of an API key in a web mapping service such as Google Maps Platform or Mapbox?

Accepted Answer

Identifying and authenticating the application to control access and track usage billing

Answer

API keys authenticate the calling application, allowing the provider to enforce usage quotas, billing, and access restrictions.

Question 5

What is 'map tiling' at zoom level 0 in a standard web map (e.g., OpenStreetMap)?

Accepted Answer

The entire world is covered by a single 256×256 pixel tile

Answer

At zoom level 0, the entire world is represented by exactly one 256×256 tile; each additional zoom level quadruples the number of tiles.

GIS - Geographic Information System Practice Test

GIS - Geographic Information System Practice Test

GIS Web GIS and Services 5