GIS Basics
What does GIS stand for?
Geographic Information Systems
What is the map design process?
Select, Arrange, Symbolize, Review, and Edit.
All keeping the overall map objective in mind.
List all the different cardinalities for joins and an example for each.
One-to-one
One-to-many
Many-to-one
Many-to-many
What are the four properties of map features that may be distorted due to the coordinate system?
Area, direction, shape, and distance.
Will the following queries work?
([Species]='Maple')OR([Species]= 'Ash')
[POP2010]>450 AND<1000
([Species]='Beech' AND [DBH]>'14') OR ([Species]= 'Birch' AND [DBH]<'14')
1. Yes. You can either have a maple tree or an ash tree. All wildcards and SQL is correct.
2. No. There needs to be another [POP2010] before the 1000.
3. Yes.
What are the three parts of the GIS process?
Data acquisition, data processing, and information output.
In regards to cartographic abstraction, what is the difference between classifying data and collapsing data?
Classifying data- involves reclassifying a detailed of attributes into a simpler set to reduce the amount of features. (Ex. different species of trees into just 'hardwoods')
Collapsing data- Changing features into simpler forms without changing the attribute data. (Ex. Detailed building footprints into just rectangles)
What does it mean for ArcMap to "project on the fly"?
If a new layer is brought into a data frame without a defined coosys, ArcMap will project the coosys based on what the defined coosys in the data frame.
What are the four different overlay operations? What are the differences between them?
Attribute data not involved:
Clip- "cookie cutter" extracts feature within the boundary.
Erase- Keeps features outside the boundary.
Attribute data involved:
Union- combine attributes and keep all features.
Intersect- combine attributes and keep only areas common to both.
What is the disadvantage of a boolean overlay?
All variables must be either true or false.
What is metadata? Why is it important?
Metadata is data about the data. Its important because it tells the user the source of the data and it that source is credible or not.
What is the difference between a feature, feature class, and a feature data set? Give me an example of each one.
Feature- a single point, line, or polygon. EX: a building, river, or road on a map.
Feature Class- A set of similar features with the same attributes. EX: Roads in SL, All buildings on campus.
Feature Dataset- A set of feature classes that all share a common coordinate system.
Name three sources of GPS error.
Satellite clock drift, atmospheric effect, signal multipathing, selective avaiability, and spoofing.
What is a boolean operator?
Essentially the same thing as an overlay except with raster data. Evaluates using map algebra two input conditions to determine a result that is true or false.
And, Or, XOR, Not
Convert 46° 22' 56" into Decimal Degrees
46.38222°
46° + 22'/60 + 56"/3600= 46.38222
What does a red exclamation point mean in ArcMap and what is one way to fix it?
A red exclamation point means your data pathway has been corrupted or lost.
In regards to cartographic abstraction, what are three ways to "falsify" spatial data?
Typify features- using representative rather than actual features.
Displace-Moving features slightly so they don't run over each other.
Exaggerate- Making features appear more important than others by making them have a larger presence.
You’re asked to digitize a new layer that contains landcover classes off of some ortho photos. What would be your first step?
Ensure the new landcover layer is in the same coosys as the rest of the data frame.
I'm attempting to buffer 50m from a St. Regis River while completing a habitat suitability analysis with vector data. While setting up my buffer, I did not select the dissolve fields button before running the dissolve tool. What is most likely going to happen to my new buffered layer?
The buffer tool will create a buffer polygon for every feature in the layer. I'll essentially have a ton of tiny little polygons.
State which display method would be best used for each of the following rasters:
slope in degrees
black-and-white aerial photo
precipitation
4-band satellite image
Geological units
Classified- Divides Values into a small number of "bins"- like graduated colors.
Stretched- scales the image values to a color ramp with 256 shades.
Stretched-""
RGB Composite- Each band is assigned a color source which brightness levels stored in each band.
Unique Values- Each value is designated it's own color. Used with categorical/ordinal data.
How are .mxd files and .lyr files different?
A .mxd file only stores file pathways, not symbology. Creating an overall "map document" that you work in ArcMap.
A .lyr file stores symbology.
Name all six numeric data classification methods.
See pg. 117-118 in book.
Jenks Method: sets the breaks at naturally occurring gaps between groups of data.
Equal-interval: Divides the values into specified # of classes of equal size.
Defined interval: Same as equal interval but the user species the size of the intervals while # of classes depends on the value range.
Quantile: Puts the same number of features in each class.
Geometric Interval: (standard deviation) bases class intervals on a geometric series.
How does the GPS measure distance?
GPS receiver has atomic clock within it. The time of the arrival of the signal is recorded inside the receiver. Then the difference in time between when it was sent to when it was received is calculated as the distance.
You are adding two rasters together in the Raster Calculator using the formula raster1 + raster2. Raster1 is in UTM projection, raster2 is in State Plane, and the default geoprocessing Environment setting for the output coordinates is USA Equidistant Conic. What coordinate system will the output raster have?
USA Equidistant Conic. It is the default setting. Which is why it's important to set your coordinate systems!
What are the major terrain features shown on topographic maps?
Spurs, Ridges, Hills, Saddles, Draws, Cliffs, Valleys, and Depressions.