Question

Describe the differences between spatial and attribute queries (use diagrams and example data if it helps). Then, for each of the GIS questions below, identify whether you would use a spatial or attribute query and describe what spatial or attribute query you would use (note that in some cases it could be both a spatial query and an attribute query):

1) Calculating the number of bee hives in the vicinity of a city centre based on a point feature class of the location of bee hives and a point feature class of the location of the city centre
2) Calculating how many suburbs have an average age over 65 based on a polygon feature class of the average age of people in each suburb
3) Calculating how many people there are in a specific suburb based on a polygon feature class of suburbs and a point of feature class of each household containing a field in the attribute table of how many people live in each household
4) Calculating the number of national parks entirely contained within a specific state that are also larger than 1,000 hectares in size based on a polygon feature class of states and a polygon feature class of national parks.

Answer 1

Spatial queries involve analyzing geometry and spatial relationships, while attribute queries focus on analyzing information stored in the attribute table. The GIS questions can be answered using a combination of spatial and attribute queries.

Step-by-step explanation:

Differences between spatial and attribute queries:

Spatial queries in GIS involve analyzing geometry and spatial relationships between features, such as finding features within a certain distance or within a particular area. Attribute queries, on the other hand, focus on analyzing the information stored in the attribute table of GIS features.

Answering the GIS questions:

1. To calculate the number of bee hives in the vicinity of a city centre, you would use a spatial query by determining the features from the point feature class of bee hives that fall within a certain radius of the city centre.
2. To calculate how many suburbs have an average age over 65, you would use an attribute query, specifically an aggregation function like COUNT, to count the number of polygons in the polygon feature class of suburbs that have an average age attribute value greater than 65.
3. To calculate how many people there are in a specific suburb, you would use a combination of a spatial query and an attribute query. First, you would use a spatial query to identify the polygon feature from the suburb feature class that contains the specific point feature from the household feature class. Then, you would use an attribute query to retrieve the number of people attribute value from the household's attribute table.
4. To calculate the number of national parks entirely contained within a specific state that are also larger than 1,000 hectares in size, you would use a combination of a spatial query and an attribute query. First, you would use a spatial query to identify the polygon features from the national parks feature class that fall completely within the boundary of the specific state. Then, you would use an attribute query to filter out the national parks with a size attribute value greater than 1,000 hectares.