GIS Web GIS and Services 3

Question 1

In the context of web mapping, what is a 'bounding box' (BBOX) parameter used for in WMS requests?

Accepted Answer

Defining the geographic extent of the requested map image

Answer

The BBOX parameter defines the spatial extent (minX,minY,maxX,maxY) of the map area to be returned by a WMS GetMap request.

Question 2

What is Mapbox GL JS primarily designed to do?

Accepted Answer

Render interactive vector tile maps in a web browser using WebGL

Answer

Mapbox GL JS is a JavaScript library that uses WebGL to render customizable, interactive vector tile maps directly in the browser.

Question 3

Which protocol is commonly used to stream real-time geographic features to a web map as they are updated?

Accepted Answer

WebSockets or Server-Sent Events (SSE)

Answer

WebSockets and SSE provide persistent connections that allow a server to push real-time feature updates to a web mapping client without polling.

Question 4

What is the role of a spatial index (e.g., R-tree) in a web GIS database?

Accepted Answer

Accelerating spatial queries by organizing geometries by bounding box

Answer

Spatial indexes like R-trees organize geometries so the database can quickly discard regions that don't intersect a query envelope, dramatically speeding up spatial queries.

Question 5

In ArcGIS REST API, what does querying a Feature Service with 'where=1=1' accomplish?

Accepted Answer

Returns all features in the layer

Answer

The SQL expression '1=1' is always true, so it matches every record in the layer, effectively returning all features.

GIS - Geographic Information System Practice Test

GIS - Geographic Information System Practice Test

GIS Web GIS and Services 3