Question 1

Digitising is the process of
A) entering the coordinates of a number of point features into a GIS via keyboard
B) converting paper maps or images to digital vector data
C) capturing vector data using GPS
D) collecting vector data through crowdsourcing

Accepted Answer

Digitising involves converting analog data into digital form. In the context of GIS, digitising refers to the process of converting paper maps or images into vector data that can be stored, manipulated and analysed in a GIS software. Choice A is incorrect as it refers to manual data entry, which is time-consuming and prone to errors. Choice C refers to a process of data collection, not digitising, and Choice D refers to a technique for collecting data through crowdsourcing, which is not strictly a digitising process.

Question 2

To digitise a paper map, one first needs to establish control points. The control points may be
A) road intersections
B) points on soil boundaries
C) points on contour lines
D) centre points of water bodies
E) all of the above

Accepted Answer

A

Question 3

The accuracy of vector data captured through digitising is independent of
A) the number of the points selected to approximate the shape of the features
B) the number of the geographical features selected to digitise from the original map
C) the density of the points selected to approximate the shape of the features
D) the accuracy of the individual points selected to approximate the shape of the features
E) the accuracy of the original map

Accepted Answer

The accuracy of vector data captured through digitizing primarily depends on the density and accuracy of the points selected to approximate the shape of the features (A, C, D) and the accuracy of the original map (E). The number of geographical features selected to digitize from the original map (B) does not directly affect the accuracy of the digitized data; it's more about the selection scope rather than the precision of the digitization process itself.

Question 4

Georeferencing an image in GIS involves
A) selecting at least three control points
B) mathematically establishing linear or non-linear relationships between image coordinates and real-world coordinates
C) transforming the image so that each location on the image can be defined in real-world coordinates
D) all of the above

Accepted Answer

Georeferencing an image in GIS involves selecting control points, establishing relationships between image and real-world coordinates, and transforming the image to define each location in real-world coordinates. Therefore, all of the above options are correct.

Question 5

Raster data can be captured
A) by means of remote sensing
B) by means of GNSS
C) through on-screen digitising
D) through tablet digitising

Accepted Answer

Raster data is typically captured through remote sensing, which involves collecting data from satellite or aerial imagery.

Question 6

Which of the following is correct?
A) Direct transfer of spatial data allows the data to be edited.
B) Direct transfer of spatial data is the main means of importing data with complex data formats.
C) Direct transfer of spatial data allows the non-native data to be translated on the fly.
D) Direct transfer of spatial data does not allow the non-native data to be translated on the fly.

Accepted Answer

Direct transfer of spatial data allows non-native data to be translated on the fly, meaning it can be converted into a format that the receiving system can understand without needing to be stored first.

Question 7

Vectorisation may
A) increase the thickness of line features
B) change the orientation of features
C) alter the attribute values of features
D) distort the shapes of features

Accepted Answer

Vectorisation can distort the shapes of features due to the conversion process from raster to vector, which may not perfectly capture the original shapes.

Question 8

Rubber sheeting
A) reproduces a map on a rubber sheet
B) mathematically stretches one map layer along a specific direction
C) mathematically stretches one map layer in all directions in order to enlarge it
D) geometrically adjusts map features to force a data layer to fit a base map

Accepted Answer

Rubber sheeting is a technique used in GIS to geometrically adjust map features in order to force a data layer to fit a base map. It involves stretching, shrinking, and distorting the data layer to fit the underlying reference data.

Question 9

An affine transformation requires a minimum of
A) 3 control points
B) 6 control points
C) 9 control points
D) 10 control points

Accepted Answer

An affine transformation, which includes operations like rotation, scaling, translation, and shearing, requires a minimum of 3 control points to be defined. These points allow for the determination of the parameters necessary for the transformation.

Question 10

Spatial data accuracy refers to
A) how close the spatial data are to a true representation of reality
B) how much detail the spatial data contain about the geographical features
C) how much bias is contained in the spatial data
D) what level of detail at which the spatial data are recorded

Accepted Answer

Spatial data accuracy refers to how close the spatial data are to a true representation of reality. It is a measure of the degree to which the data represents the real-world features and their characteristics.

Question 11

Spatial data precision refers to
A) how close the spatial data are to a true representation of reality
B) how much detail the spatial data contain about the geographical features
C) how much bias is contained in the spatial data
D) what level of detail at which the spatial data are recorded

Accepted Answer

The answer of Spatial data precision refers to
A) how close...

Question 12

High accuracy implies high precision and vice versa

Accepted Answer

Accuracy and precision are two different things in measurement. Accuracy refers to the closeness of a measured value to its true value, while precision refers to the closeness of two or more measurements to each other. It is possible for a measurement to be precise but not accurate, or accurate but not precise.

Question 13

The positional accuracy of a point feature is associated with
A) errors in its recorded x coordinate
B) errors in its recorded y coordinate
C) errors in its recorded z coordinate
D) all the above

Accepted Answer

The positional accuracy of a point feature is associated with errors in all its recorded coordinates- x, y, and z.

Question 14

The positional accuracy of a line feature is associated with
A) errors in the locations of the individual points selected to represent the feature
B) errors in locating well-defined points along the line feature
C) both a) and b)
D) neither a) nor b)

Accepted Answer

The positional accuracy of a line feature is affected by errors in the locations of the individual points selected to represent the feature, as well as errors in locating well-defined points along the line feature. Therefore, both options a) and b) are correct.

Question 15

The accuracy of the air temperature data recorded at a number of geographically distributed meteorological stations can be assessed using
A) RMSE
B) cross-tabulation
C) standard deviation
D) mean

Accepted Answer

RMSE (Root Mean Squared Error) is a commonly used metric for assessing the accuracy of a model's predictions or in this case, the accuracy of air temperature data. It measures the difference between the actual values and the predicted values, taking into account both the magnitude of the differences and the number of values being compared. The lower the RMSE, the better the accuracy of the data. Cross-tabulation, standard deviation, and mean are not ideal for assessing the accuracy of air temperature data as they do not account for the magnitude of the differences between actual and predicted values.

Question 16

The accuracy of soil classification on a soil map can be assessed using
A) RMSE
B) cross-tabulation
C) standard deviation
D) mean

Accepted Answer

Cross-tabulation is a method used to compare the accuracy of a map with field observations. It involves comparing the observations from the field with the classified areas on the map. This method can provide a measure of agreement between the map and the field observations in terms of the number of correctly classified areas and the number of areas that were misclassified. RMSE, standard deviation, and mean are statistical measures that can assess the accuracy of continuous data, but they are not appropriate for soil classification.

Question 17

With the classification error matrix below, what is the overall accuracy of the land use classification?
$\begin{array}{|l|l|l|l|l|}
\hline & \text { Urban } & \text { Forest } & \text { Cropland } & \text { Total } \
\hline \text { Urban } & 7 & 2 & 1 & 10 \
\hline \text { Forest } & 2 & 25 & 8 & 35 \
\hline \text { Cropland } & 3 & 1 & 51 & 55 \
\hline \text { Total } & 12 & 28 & 60 & 100 \
\hline
\end{array}$
A) 100%
B) 27.7%
C) 29%
D) 83%

Accepted Answer

The overall accuracy is calculated by dividing the sum of the correctly classified instances by the total number of instances. In this case, the sum of the correctly classified instances is 7+25+51=83. 
Therefore, the overall accuracy = 83/100 = 83%.

Question 18

Lineage of a spatial dataset does not describe
A) the scale of its source data
B) the date of its source data
C) the data capture and processing methods
D) the layout of its source maps

Accepted Answer

Lineage of a spatial dataset describes the process of how the data was created, modified or transformed. It includes information about the data capture and processing methods, as well as any sources of the data used. It does not describe the scale of its source data, the date of its source data, or the layout of its source maps.

Question 19

Manual digitising is a significant source of errors in spatial data. But which of the following is not typically an error from manual digitising?
A) undershoot and overshoot
B) spikes
C) displacement
D) incomplete areal coverage
E) knot

Accepted Answer

Incomplete areal coverage is not typically an error from manual digitising. It is more likely to occur due to limitations in data sources or incomplete information. Undershoot and overshoot, spikes, displacement, and knots are all common errors that can occur during manual digitising.

Question 20

Vector to raster conversion may cause loss of information because
A) small polygons could be lost
B) a point feature can only be represented using a single grid cell
C) real-world locations of geographical features can no longer be determined
D) measurement becomes inaccurate

Accepted Answer

Small polygons could be lost during vector to raster conversion because the resolution of the raster grid may not be fine enough to capture small features, leading to a loss of detail.

Quiz 3: Spatial Data Input and Manipulation

Digitising is the process of

To digitise a paper map, one first needs to establish control points. The control points may be

The accuracy of vector data captured through digitising is independent of

Georeferencing an image in GIS involves

Raster data can be captured

Which of the following is correct?

Vectorisation may

Rubber sheeting

An affine transformation requires a minimum of

Spatial data accuracy refers to

Spatial data precision refers to

High accuracy implies high precision and vice versa

The positional accuracy of a point feature is associated with

The positional accuracy of a line feature is associated with

The accuracy of the air temperature data recorded at a number of geographically distributed meteorological stations can be assessed using

The accuracy of soil classification on a soil map can be assessed using

Lineage of a spatial dataset does not describe

Manual digitising is a significant source of errors in spatial data. But which of the following is not typically an error from manual digitising?

Vector to raster conversion may cause loss of information because