Spatial Joins

Question 1

Attribute joins are based on a common field. What are spatial joins based on?

Answer 1

Spatial joins are similar to table joins:
 There is a source and a destination
 User must take into account the cardinality of the feature classes
 Spatial joins are not based on a common attribute
 Spatial joins are based on a common spatial relationship
 The result of a spatial join is a new feature class

Question 2

List the two spatial relationships on which spatial joins are based?

Answer 2

 One feature inside another - containment

 One feature closest to another - proximity

Question 3

What are inside joins? Explain.

Answer 3

features inside a polygon

Question 4

What are distance joins? Explain.

Answer 4

features closest to other features

Question 5

An attribute join temporarily appends the fields of the source table to the destination
table. In this respect, how is a spatial join different from an attribute join?

Answer 5

The tables of the participating feature classes are not affected
 New feature class has fields from both input tables

Question 6

What determines the geometry of the output feature class in a spatial join?

Answer 6

Output layer has the same geometry type as destination layer

Question 7

If an airports feature class is joined to a cities feature class, with cities as the destination
layer, what type of features, cities or airports, will be contained in the output feature
class?

Answer 7

Cities = Points

Question 8

When using a distance join, what fields, if any, are created automatically?

Answer 8

Distances are given in stored map units

Question 9

True or false? In an inside join the records of two features will be joined only if one of the
features is completely inside the other feature

Answer 9

True

Question 10

True or false? In an inside join one of the feature classes must always be a polygon
feature class

Answer 10

True

Question 11

What is the rule of joining? Explain.

Answer 11

Cardinality rules apply

Must be projected for accuracy

Question 12

Based on cardinality, spatial joins can be grouped into two categories. What are these
categories?

Answer 12

Simple joins - one to one or many to one

Summarised joins - one to many

Question 13

What type of spatial joins can be performed if the cardinality is one-to-one or many-toone?

Answer 13

Simple joins

Question 14

What type of spatial joins can be performed if the cardinality is one-to-many or many-tomany?

Answer 14

Summarised joins

Question 15

Taking into account cardinality and spatial relationship, spatial joins can be grouped into
four categories. List these categories.

Answer 15

Simple Inside
Simple Distance
Summarised Inside
Summarised Outside

Question 16

If an airports feature class is joined to a cities feature class (please see the illustration in
Figure 1), with cities as the destination layer, what is the cardinality between the two
feature classes?

Answer 16

Many to many

Question 17

In the question above, what type of spatial join would be performed? Please make
reference to the spatial relationship as well as the cardinality. Question 16.

Answer 17

Summarised Distance

Question 18

In Question 16, assuming that the cities feature class has only one numerical field
(POP2007), and that the airports feature class has no numerical fields, how many fields, if
any, would be generated automatically as a result of performing the spatial join?
Important: Try to answer the question without using the ArcGIS software.

Answer 18

2 numerical fields
one from the OG cities POP2007
+
Distance from the summarised distance

Question 19

If a cities feature class is joined to an airports feature class (please see the illustration in
Figure 1), with airports as the destination layer, what is the cardinality between the two
feature classes?

Answer 19

one to many

Question 20

In the question above, what type of spatial join would be performed? Please make
reference to the spatial relationship as well as the cardinality.

Answer 20

Simple Distance

Question 21

In Question 19, assuming that the airports feature class has no numerical fields, and that
and that the cities feature class has one numerical field (POP2007), how many fields, if
any, would be generated automatically as a result of performing the spatial join?
Important: Try to answer the question without using the ArcGIS software.

Answer 21

?

Question 22

What is Euclidean distance (pronounced \yü-ˈkli-dē-ən)? Explain.

Answer 22

he Euclidean Distance tool is used frequently as a stand-alone tool for applications, such as finding the nearest hospital for an emergency helicopter flight. Alternatively, this tool can be used when creating a suitability map, when data representing the distance from a certain object is needed.

Question 23

What is Manhattan distance?

Answer 23

The distance between two points measured along axes at right angles. eg following roads on a grid system

Question 24

Why is it not recommended to work with geographic coordinate systems when
performing distance joins?

Answer 24

Using a GCS or inappropriate projection may yield incorrect results

Question 25

Explain why it is difficult to convert degrees into linear units of measurement such as
kilometres or miles.

Answer 25

Because degrees change depends on where you are on the global, wider at certain middle places on earth and narrow at the poles.

Question 26

A GIS analyst is performing a distance join between two feature classes. All the feature
classes use a geographic coordinate system. However, the data frame uses a projected
coordinate system with metres as the linear unit of measurement. What will be the units
of measurement in the distance field for the output feature class?

Answer 26

Using a GCS or inappropriate projection may yield incorrect results

Question 27

. In the question above, what steps should the GIS analyst take to ensure that the units in
the distance field are as accurate as possible?

Answer 27

Project coordinate system

Question 28

Carry out an Internet search and provide a brief explanation about the State Plane
Coordinate System.

Answer 28

The State Plane Coordinate System (SPS or SPCS) is a set of 124 geographic zones or coordinate systems designed for specific regions of the United States.

Question 29

What are the two most commonly used map projections in the State Plane Coordinate
System?

Answer 29

Most state plane zones are based on either a transverse Mercator projection or a Lambert conformal conic projection.

Question 30

A GIS analyst would like to perform a distance join using statewide data for the state of
Kansas. In this case, would it be recommendable for the GIS analyst to use a State Plane
Coordinate System?

Answer 30

No! Must be a system that covers the area specfied.

Question 31

What is the “one-sixth rule”? Explain

Answer 31

For custom projections, for Albers projections to find standard parellels (Latidtude)

Question 32

A GIS analyst would like to create a custom conical projection for the state of Tennessee.
She would like to use the one-sixth rule to develop a custom map projection for this state.
List all the required projection parameters she would need to calculate.

Answer 32

Central Meridian
Standard Parellel 1
Standard Parellel 2
Latitude of Origin

Fasle easting and northings

Question 33

A GIS analyst would like to create a custom map projection for the state of Illinois. She
would like to use the one-sixth rule to develop a custom map projection for this state.
Would you recommend that she uses a UTM projection instead? Explain.

Answer 33

UTM would Longitude degrees cover Illinois

This would be the best option for the least amount of distortion

Does not need to use one-sixth rule

Question 34

In the question above, would you recommend that the analyst uses a Transverse
Mercator projection? Explain.

Answer 34

Yes, it fits the state as it runs north to south

Question 35

Albers equal-area conic projection:

a. Who developed the Albers Equal-Area Conic projection?
b. How many standard parallels does it have?
c. What property is best preserved by this projection?
d. In which areas are shape and distance best preserved?
e. What is the maximum range of latitude for this projection?

Answer 35

a. Heinrich C. Albers
b. 2
c. Area
d. between standard parallels
e. 30-35 degrees north to south

Question 36

Lambert Conformal Conic projection:

a. Who developed the Lambert conformal conic projection?
b. How many standard parallels does it have?
c. What property is best preserved by this projection?
d. In which areas are distance and area best preserved?
e. What is the maximum range of latitude for this projection?

Answer 36

a. Johann Heinrich Lambert
b. 1 (scale factor less than 1) or 2
c. Shape
d. Standard parallels
e. Lat max 35 degrees

Question 37

Equidistant Conic projection:

a. Who developed the Equidistant Conic projection?
b. How many standard parallels does it have?
c. What property is best preserved by this projection?
d. In which areas are shape and area best preserved?
e. What is the maximum range of latitude for this projection?

Answer 37

a. Claudius Ptolemy
b. 1 or 2
c. Distance - True along the meridians and the standard parallels
d. Standard parallels
e. Lat - 30 degrees max diff