LDA 150 Final Study Guide

Three major sources of error in GPS measurement are:

A) Satellite, receiver, atmospheric interference

B) Satellite, and ground control stations

C) Receiver, and atomic clocks

D) Ionosphere, troposphere, and atmosphere

A) Satellite, receiver, atmospheric interference

B) Satellite, and ground control stations

C) Receiver, and atomic clocks

D) Ionosphere, troposphere, and atmosphere

To create road buffers as a raster, you must start by executing the_________ tool on the vector road layer.

A) Euclidean Distance

B) Neighborhood Statistics

C) Euclidean Direction

D) Raster Buffer

A) Euclidean Distance

Do you need internet to use GPS.

A) True

B) False

A) True

Tobler's law states that_________.

A) Boolean rasters may have values of one or zero only

B) values close together are more likely to be similar

C) aggregation schemes may affect the appearance of maps

D) each record should have one and only one match in the join table

B) values close together are more likely to be similar

A GPS signal consists of

A) A secret digital code,

B) A message called selective availability

C) A navigation message, One or more carrier waves, One or more digital codes

D) One or more carrier waves only

C) A navigation message, One or more carrier waves, One or more digital codes

Map algebra is a technique for_________.

A) analyzing stacks of raster maps using mathematical or Boolean operators

B) determining the densities of points in a dataset

C) resampling rasters so that they have the same cell size

D) determining the minimum, maximum, and average values in a raster

A) analyzing stacks of raster maps using mathematical or Boolean operators

A better spatial interpolation method should have a _____ RMS error.

A) higher

B) lower

B) Lower

What raster function would you use to find the areas of a slope raster that exceed 20 degrees?

A) Aspect

B) Slope

C) Zonal Statistics

D) Raster Calculator

D) Raster Calculator

Estimating values for a new raster between measurements taken at point locations uses

the_________ function.

A) Neighborhood Statistics

B) Interpolation

C) Zonal Statistics

D) Density

B) Interpolation

You have a point dataset of wells near the ocean, with a field that contains chloride values. You want to create a raster showing the severity of saltwater intrusion using the chloride values. You

could use the_________ tool.

A) Euclidean Distance

B) IDW

C) Raster Calculator

D) Zonal Statistics

B) IDW

When does automatic resampling of rasters occur?

A) whenever two input rasters with different cell sizes are used in a function

B) whenever rasters are converted to feature classes

C) whenever the Raster Calculator is used

D) whenever neighbor statistics are performed

A) whenever two input rasters with different cell sizes are used in a function

Why is it important to store rasters in projected coordinate systems that preserve distance and/or area?

A) Because many raster tools involve distance and/or area-based algorithms.

B) Because geographic coordinate systems have lower resolutions.

C) Because Spatial Analyst will not process unprojected rasters.

D) Because map algebra requires the cell sizes and locations to match.

A) Because many raster tools involve distance and/or area-based algorithms.

Select the definition of the term "reclassify function".

A) replaces sets or ranges of values in a raster with different sets of values

B) counts the number of occurrences in a circle of specified size

C) estimates raster cell values between known point measurements

D) calculates a value for a target cell based on surrounding values in a defined

region

A) replaces sets or ranges of values in a raster with different sets of values

 The semivariogram demonstrates the degree of dissimilarity between points as a function of separation distance.

A) True

B) False

B) False

In a weighted overlay, the weight must sum to 1.

A. False

B. True

B. True

A single dimensionless number called Dilution of Precision (DOP) indicates errors associated with satellite geometry. The lower value of DOP is better.

A. True

B. False

A. True

Which of the following is a stochastic (geostatistical) interpolation method?

A) inverse distance weighted

B) Thiessen polygons

C) thin-plate splines

D) kriging

E) none of these is correct

D) kriging

 A higher power for the IDW method means that:

A) Closer control points will have greater influence on the estimation

B) Closer control points will have less influence on the estimation

C) Control points will be equalized in terms of their influence on the

estimation

D) None of the above

A) Closer control points will have greater influence on the estimation

Ideally, all rasters being analyzed are stored in the same projection, extent, and cell size

A. to avoid the introduction of resampling errors

B. to ensure that the map algebra operators work correctly

C. to eliminate the possibility of distance and area distortion

D. to ensure that the output rasters are stored in the correct location

A. to avoid the introduction of resampling errors

Why is it important to ensure that your criteria fit the problem that you are trying to solve?

A.The criteria primarily identifies the source data that you should use.

B.Your criteria dictate which type of suitability model that you should

use.

C. The criteria sets the objective for the suitability analysis.

D. The source data, geoprocessing tools, and transformation methods vary based on the way that the criteria is defined.

D. The source data, geoprocessing tools, and transformation methods vary based on the way that the criteria is defined.

Which one of the following functions uses a moving window?

A. Zonal Statistics

B. Summary Statistics

C. Raster Statistics

D. Neighborhood Statistics

D. Neighborhood Statistics

An analysis mask is used to.

A. Calculate zonal statistics for a given region

B. Add or multiply a raster by a constant value

C. Ensure that the output grid is not larger than the input grids

D. Screening out regions outside an area of interest by giving the cells No Data values

D. Screening out regions outside an area of interest by giving the cells No Data values

A cost-distance analysis is used to find.

A. The shortest distance between two locations

B. The direction of travel between two locations

C. The easiest path between two locations

D. The elevation difference between two locations

C. The easiest path between two locations

When performing exploratory spatial data analysis, it was determined that the sampled values were not normally distributed. When creating a prediction surface, how could you adjust the semivariogram model in order to meet the normally distributed assumption?

A. Increase the subset size

B. Increase the maximum number of neighbors

C. Increase the number of simulations

D. Apply an empirical transformation

D. Apply an empirical transformation

Which of the following best describes the primary difference between deterministic and geostatistical spatial interpolation techniques?

A. Deterministic methods use mathematical formulas, while geostatistical methods are based on spatial statistics.

B. Deterministic methods do not allow user-defined parameters, whereas

geostatistical methods do.

C. Geostatistical methods are less reliable as they depend on the spatial

configuration.

D. Deterministic methods provide estimates of prediction error, while geostatistical methods do not

A. Deterministic methods use mathematical formulas, while geostatistical methods are based on spatial statistics.

What is the primary purpose of using cross-validation in geospatial analysis in GIS?

A. To maximize the error in predictions.

B. To validate the model by excluding each input sample point systematically.

C. To minimize the need for statistical analysis.

D. To increase the complexity of the model

B. To validate the model by excluding each input sample point systematically.

How does the theory of relativity proposed by Einstein influence the functioning of GPS

A. By adjusting for the time dilation effects due to the speed of the satellites.

B. By providing the mathematical framework for elliptical satellite orbits.

C. By determining the geographical layout of continents.

D. By predicting weather patterns for satellite interference.

A. By adjusting for the time dilation effects due to the speed of the satellites.

Which code of the GPS signal operates at a frequency of 1.023 MHz?

A. L1 Carrier

B. C/A Code

C. Navigation System Data

D. P-Code

B. C/A Code

Which factor does NOT contribute to satellite errors?

Orbit

Visibility

Attitude Control

Geometry of satellites

Attitude Control

Other satellite-based GNSS systems – other than GPS are:

A) GLONASS

B) Galileo

C) BieDou-3

D) All the above

D) All the above

31. Create a new raster by converting each cell value from % slope to slope in degrees (type the new  cell values). Formula?

Hint: Slope in degrees = artan(slope in percent/100) 

What are some example applications for suitability modeling? 

1. locating the optimum habitat for an endangered species

2. optimum location for the construction of anything (dam, road, military base, hospital, park, Target, etc.)

Explain the different types of suitability modeling. 

1. binary: involves a binary final answer of 1 or 0, suitable or unsuitable

2. weighted: allows for a range of final answers & allows certain layers to have more influence (weight) on the results of the model

3. fuzzy logic: assign membership values to locations that range from 0-1, 0 = nonmembership or unsuitable site and 1 = membership or suitable site

Explain the difference between local, neighborhood, zonal and global raster operations.

1. Local: based on cell-by-cell analysis - can create a new raster from either a single input raster or multiple input rasters

2. Neighborhood: involves a focal/target cell & set of its surrounding cells

3. Zonal: examines group of cells that occur within a uniform feature type

4. Global: examine entire area extent of dataset

Describe how the semivariance can be used to quantify the spatial dependence in a data set.

semivariance: measure of the degree of spatial dependence among points used in kriging

if spatial distance…

a. known points close together = small semivariance

b. known points farther apart = large semivariance

What are the limitations associated with deterministic interpolation?

1. no clear guidance on how large the radius of influence is/should be

2. no estimate of how good the interpolation is (i.e. no measure of error or uncertainty)

What is spatial autocorrelation?

a spatial statistic that measures the relationship among values of a variable according to the spatial arrangement of the values

With the aid of a semivariogram figure, describe what different features represent?

A = Partial Sill

B = Nugget, very small separation distances

C = Range, or the distance where the model

D = Sill, or the value of the ordinate at which the variogram levels off

What are the key data assumptions in geostatistics?

• The phenomenon must be spatially continuous.
• The random local-scale variations in the values of a phenomenon are spatially autocorrelated
• Data must be stationary
• Measured values follow a normal or bell-shaped or Gaussian curve.

 In geostatistical spatial interpolation, why is it important to verify the fit at a local scale?

A key data assumption for geostatistical interpolation states that the random local-scale variations in the values of a phenomenon are spatially autocorrelated. In terms of the semivariogram chart, local scale is represented as a distance range. Pairs of sample points with distances less than the range have values that are spatially autocorrelated. It is important that it is properly fitted within the range because these values contribute most to the predicted values. At distances greater than the range, the fit can begin to diverge.

Calculate the error in positioning associated with errors of 5 nanoseconds and 5 microseconds

convert both nanoseconds and microseconds into seconds. multiple by the speed of ligt = 299,792,458 m/s.

In your own words, explain the difference between 2D and 3D trilateration and describe when  each is used.

trilateration: process of GPS receiver using data from satellites to locate to a specific point on the Earth

1. 2-D: uses at least 3 known points and the distances from an unknown point to these 3 points to calculate a position in a plane (X, Y coordinates)

2. 3-D: extends to 3-D space, requiring at least 4 known points and distances to calculate a position in 3 dimensions (X, Y, Z coordinates)

Describe the structure of a GPS signal.

GPS signal = carrier wave (L1, L2) + Codes (C/A, P) + Navigation Message (N)

Why is the L band used to transmit GPS radio signals?

L bands can penetrate clouds, fog, rain, storms, and vegetation

 Which errors can be eliminated by DGPS?

Satellite clock errors, orbit errors and atmospheric errors can be minimized or eliminated using DGPS