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54 Cards in this Set
- Front
- Back
When you take a layer of data, perform an operation, and come out with a new layer, what process have you performed? |
Basic Spatial Analysis |
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Name in order the 3 main steps to Basic Spatial Analysis. |
1. Input 2. Spatial Operation 3. Output |
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When one input creates many outputs, what has happened? |
basic spatial analysis |
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Name 3 operations involved with Exploration |
1. Descriptive Statistics 2. Graphing/Charting 3. Attribute Queries |
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What operations are involved with Attribute Queries? |
1. set algebra (<,>,+,-) 2. boolean algebra (AND, OR, NOT) |
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What operation is involved with Spatial Selection? |
spatial queries |
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Spatial selection involves operations such as spatial queries. What can you do with spatial queries? |
1. Cursor or Graphic select
2. Select by spatial relationship (Proximity / Adjacency, or Containment) 3. Intersection |
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Spatial Queries are based on |
location |
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By choosing 'Containment' when selecting by spatial relationship, what are you essentially selecting? |
Items that fall completely within a selected space. |
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How can you make a selection based on both spatial and non-spatial attributes? |
1. Dissolving 2. Buffering 3. Overlay 4. Other map manipulations |
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Which spatial selection aggregates features based on specific attributes, essentially combining like-features on a data layer and removing boundaries between data if the data shares boundaries? |
Dissolve |
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Describe the Dissolve function of Spatial Selection |
Combines like-features on a data layer and removes the boundaries between data when it shares outer boundaries. |
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Describe an example of how you might use the Dissolve spatial selection operation. |
A map depicts climate regions of the US. Dissolve removes the state boundaries and keeps boundaries between only the different climate regions. |
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Which spatial selection operation finds an area within a specified distance around a feature? |
Buffer |
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Describe the spatial selection operation: Buffer |
finds an area within a specified distance around a feature. |
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look up variable distance buffer |
lecture 7 |
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Which spatial selection operation essentially takes 2 input layers and creates one output layer? |
Overlay |
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Describe how the spatial selection operation Overlay works. |
combines different data layers, both spatial and attribute data, to create a result layer. |
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What condition must the Overlay operation meet to be performed? |
all data layers must use a common coordinate system |
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What 2 different options do you have when performing an overlay? |
1. union 2. intersect |
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Describe a Union overlay |
Combines all of 1st and 2nd layer, regardless if they overlap. (Think "OR") |
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Describe an Intersect overlay. |
Only keeps areas that are shared between all input layers. (Think "AND") |
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Name a map manipulation that extracts info from a different layer to create a "cookie cutter." |
Clip |
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Basic raster data is a |
grid of pixels |
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Is raster data continuous or non-continuous? |
continuous |
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What type of data does raster data NOT recognize? |
entity-attribute |
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Raster data recognizes only which type of data? |
spatial |
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What is a disadvantage to raster data? |
database is much larger |
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Name the 7 Raster GIS Conventions |
1. Map layer 2. Square mesh 3. Resolution 4. Orientation 5. Zone 6. Class 7. Value |
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What is the most important quality to remember about raster map layers? |
each layer has a different theme (such as land cover, etc.) |
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What is the square mesh component of raster data? |
the grid composed of rows and columns |
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Each cell of the square mesh contains a |
numeric value |
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What does resolution determine? |
what size the grid cell is |
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What is a raster zone? |
a group of continuous pixels with the same value |
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What is a raster class? |
a group of zones |
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Describe raster values. |
Every cell must have a numeric value. There can be no empty space with no value. |
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What type of image has the most values? |
photographic images |
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What is the "Mixed Pixel Problem"? |
Some pixels may contain information with multiple values, but the cell can only have one numeric value. |
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Name and describe 3 ways to alleviate the Mixed Pixel Problem |
1. centroid: pick the value that's in the center of the cell 2. transverse: place a line going thru the middle of the cell and choose the value the line crosses most 3. percentage: pick the value that makes up the highest percentage of the cell |
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Name the 2 types of Raster GIS data layers |
1. Image 2. Gridded Area-Class Map Layer |
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Look up Image vs. Gridded Area-Class Map Layers |
pp lecture 8 |
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List the 3 main Raster analytic operators |
1. Reclass / Recode 2. Overlay 3. Distancing |
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Why might you choose to Reclass/Recode? |
to separate a pixel from the rest |
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Which raster analytic operator changes the value of a pixel? |
reclass/recode |
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What raster analytic operator is the same idea as "Buffer," but for raster? |
distancing |
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What is better for cartography - raster or vector? |
vector |
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How many area class values can you have? |
only 7 |
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Name the 4 types of terrain analysis |
1. DEMs (Digital Elevation Models) 2. Derivative surfaces and functions 3. applications using elevation models 4. TINs (Triangulated Irregular Networks) |
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Name 3 ways to generate digital elevation models (DEMs) |
1. photogrammetry 2. scanning 3. spatial interpolation |
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What can you determine using DEMs and DEM derivative surfaces? |
1. drainage basins and watersheds 2. drainage networks and channels 3. peaks, pits, and other landforms |
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What can you model using DEMs and DEM derivative surfaces? |
1. hydrologic flow 2. forest fires |
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How do DEMs determine drainage networks? |
Use algorithms to determine the flow direction using either D4 or D8 movement |
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LEARN AND UNDERSTAND D4, D8 MOVEMENT |
lecture 10 |
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Name 9 attributes that can be computed from DEMs |
1. elevation 2. slope 3. aspect 4. verticial profiling 5. watershed analysis 6. ridge 7. wetness index 8. viewshed 9. surface curvature |