Data Acquisition

Question 1

What is Quality Control?

Answer 1

Checking the data to make sure it is accurate and complete

Question 2

What is Quality Assurance?

Answer 2

a process for improving the quality of a product or service by anticipating and addressing quality problems.

Question 3

What is Ground-truthing?

Answer 3

-Raster quality control method
-Comparing the interpolated values on a raster to either the real world or an alternative data source, such as a aerial photo

Question 4

What are Imprecision Causes?

Answer 4

-Data collection device limitations
-Data collection errors
-Data entry errors
-Data storage limitations
-Data storage mistakes

Question 5

What are the accuracy tiers of GPS Data?

Answer 5

-Consumer/Recreational grade GPS: 30m
-Mapping grade: 3-5m/0.5-2m
-Survey and military grade GPS: 1m-1mm

Question 6

What is Geodatabase Topology?

Answer 6

-A model of the relationships that exist among features in a geodatabase
-Stores the properties of the topology with the data
-Defines rules on relationships among features
-Provides a system for giving priority to features of greater accuracy

Question 7

What is Map Topology?

Answer 7

-Used to maintain coincident edges
-Only exists within an edit session, thus not stored with the data

Question 8

What is Raster Resolution Limitations?

Answer 8

If the device can only collect data every 10 feet, you cannot have a 1-foot pixel

Question 9

What is Georeferencing?

Answer 9

The process of aligning unreferenced data to a dataset that is spatially referenced

Question 10

What are the Georeferencing Transformation Types?

Answer 10

Polynomial, spline, adjust, projective, and similarity

Question 11

What is Georeference Transformation?

Answer 11

When you’ve created enough control points, you can transform the raster dataset to the map coordinates of the target data.

Question 12

What is a World File (Georeferencing)?

Answer 12

A six line plain text file used by geographic information systems (GIS) to georeference raster map images.

Question 13

What is the Transformation Order of Priority?

Answer 13

1. The header file (if the image type supports one)
2. The World File (used first if the Use world file to define the coordinates of the raster checkbox is checked)
3. The row/column information of the image

Question 14

What are the Data Collection Methods?

Answer 14

-GPS
-Surveying
-Georeference and digitize
-Remotely-sensed imagery

Question 15

Using the Satellites

Answer 15

GPS receiver listens to signals from satellites
-Calculates its current distance from each satellite
-Knows where each satellite is at the moment it is sent the radio signal
-Determines its own location on the earth, reports it in lat/long WGS84

Question 16

What is the GPS Standard Positioning Service Performance Standard?

Answer 16

The government commits to broadcasting the GPS signal in space with a glocal average User Range Error (URE) of ≤ 7.8 meters (25.6 feet), with 95% probability.

Question 17

What is Positional Dilution of Precision (PDOP)?

Answer 17

Describes how good the satellite configuration is for collecting accurate points. Lower dilution equals better quality point.

Question 18

What are the GPS systems around the world?

Answer 18

-NAVSTAR (USA)
-GLONASS (Russia)
-IRNSS (India)
-Galileo (European Union)
-Compass/Beidu (China)

Question 19

What does the Code Division Multiple Access (CDMA) do?

Answer 19

All satellites transmit on the same frequencies but receivers use CDMA to keep signals separated into channels

Question 20

GPS Transmissions include what information?

Answer 20

-Time the signal was sent
-Satellite position at time of signal

Question 21

What are the GPS signal frequencies?

Answer 21

-L1 (mapping grade)
-L2 (survey grade)

Question 22

What is signal-to-noise ratio (SNR)?

Answer 22

The ratio of signal power to base noise level of the GPS observation. Lower value means lower signal strength and more noise, so higher values are better.

Formula: Signal Strength/Noise Level

Question 23

What is Differential Correction?

Answer 23

A technique used to reduce the systematic errors that decrease the accuracy of GPS positions.

Question 24

What is a Virtual Reference Station (VRS)?

Answer 24

A network of reference stations that monitor GPS signals and log corrections for reference

Question 25

What is Real Time Kinematic (RTK)?

Answer 25

Real time differential correction using base station (or network) and a rover

Question 26

What is a Satellite-Based Augmentation System?

Answer 26

Systems that send correction signals from ground station to GPS receivers via satellites.

Question 27

What are benchmarks (control stations)?

Answer 27

Known points around the world that are used for measuring by surveyors.

Question 28

What are instruments used by surveyors?

Answer 28

Theodolites, transits, and total stations

Question 29

What is the difference between a Unmanned Aerial Vehicle (UAV) and a Unmanned Aerial System (UAS)?

Answer 29

UAV is the drone itself, while UAS is the drone plus the equipment on the ground controlling the drone

Question 30

What are some laws for flying drones?

Answer 30

-Require a license to fly commercially
-Must fly at under 400 ft without a waiver
-Must be 55 lbs or less
-Must be flown in line of site
-Must not be flown over 100 mph
*Some of these rules can be waived using a Part 107 waiver