Lda final

Three major sources of error in GPS measurement are

satellite, receiver, atmospheric interference

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

Euclidean Distance

Do you need internet to use GPS

yes

Toblers law

Values close together are more likely to be similar

A GPS signal consists of

a navigation message, one or more carrier waves, one or more digital codes

Map algebra is a technique for

analyzing stacks of raster maps using mathematical or boolean operators

A better spatial interpolation method should have a ___ RMS error

lower

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

Raster Calculator

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

Interpolation

You have a point dataset of wells near a 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 ___ tools

IDW

When does automatic resampling of rasters occur

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?

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

Reclassify Function

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

True

In a weighted overlay, the weight must sum to 1

true

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

True

Which of the following is a stochastic interpolation method

Kriging

A higher power for the IDW method means that

Closer control points will have a greater influence on the estimation

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

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

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

Which function uses a moving window

Neighborhood Statistics

An analysis mask is used to

screening out regions outside an area of interest by gibing the cells NO data values

A cost-distance analysis is used to find

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

apply an empirical transformation

What describes the primary difference between deterministic and geostatistical spatial interpolation techniques

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

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

by adjusting for the time dilation effects due to the speed of satellites

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

C/A code

Which factor does not contribute to satellite erros

attitude control

Other satellite-based GNSS systems, other than GPS are

• GLONASS

• Galileo

• BieDou-3

What are some examples of applications for suitability modeling

• locating the optimum habitat for an endangered speices

• optimum location for the construction of a dam, road, millitary base, hospital, store, or a park in a city

Explain different types of suitability modeling

Binary: involves a binary final answer

• 1= suitabile

• 0= unsuitabile

Weighted: allows for a range of final answers

• from 1-10

• allows certain layers to have more inluence on the results of the model

Fuzzy: assigns membership values to locations that range from 0 to 1 (ESRI)

• 0= non-membership or unsuitable

• 1= membership or suitable site

Explain different raster operations

• local: examines only a single target cell during analysis

• neighborhood: examines the relationship of a target cell to proximal surrounding cells

• Zonal: examines groups of cells that occur within a uniform feature type

• Global: examines the entire area extent of a dataset

Explain how a semi variance used to quantify spatial dependence in a data set

It is used to quantify the spatial dependence in a data set because it spatial dependence does exist in the data set kmown points that are close to each other are expected to have small semivarinces also known points that are further apart are expected to hae

What limitations are associated with deterministic interpolation

• no clean guidance on how large the radius of influence/neighborhood is

• No estimate of how good the interpolation is (ex: no measure of error or uncertainty)

What is spatial autocorrelation

It measures of the degree to which nearby locations are more similar in value than locations that are farther away.

What are the key data assumptions in geostatistics

• the phenomenon must be spatially continuous

• the random local-scale variations in the values of the phenomenon are spatially autocorrelated

• data must be stationary

• measured values follow a normal or bell-shaped or gaussian curve

Why is it important to verify the fit of a local scale

Because these values contribute most to the predicted values. At distances greater than the range, the fit can begin to diverge.

Calcuate error positioning with errors of 5 nanosecs and 5 microsecs in a clock

(time) x (speed of light)

Explain 2D and 3D trilateration and how they are used

Trilateration is determining a position by knowing your distance from at least 3 known points. In GPS these are known as satellites

• 3D trilateration involves circles that solve x,y,z

• 2D trilateration intersect spheres that solve x,y

Explain the structure of GPS signal

They contain satellite coordinates as a function of time, clock correction, satellite health, satellite almanac, and atmospheric correction model

What is L band used to trasmit GPS radio signals

L band waves are used for GPS units because they are able to penetrate clouds, fog, rain, stroms, and vegetations

What errors are erased by DGPS

• satellite clock errors

• orbit errors

• atmospheric errors can be minimized or eliminated using DGPS

Different parameters of a semivariogram

a) partial sill: difference between sill and nugget

b) nugget: represent errors in measurements or variation at distance smaller than the sampling interval

c) range: the distance where the model first flattens (ex: there is no spatial autocorrelation)

d) sill: the value of the coordinate at which the variogram levels off.