Term
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Definition
| an ArcInfo Grid exchange file |
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Term
DEM
(Digital Elevation Model) |
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Definition
| This format consists of a raster grid of regularly spaced elevation values. In their native format, they are written as ANSI-standard ASCII characters in fixed-block format. |
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Definition
| A proprietary ESRI format that supports 32-bit integer and 32-bit floating-point raster grids. Grids are useful for representing geographic phenomena that vary continuously over space and for performing spatial modeling and analysis of flows, trends, and surfaces such as hydrology |
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PNG
(Portable Network Graphics) |
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Definition
| Provides a well-compressed, lossless compression for raster files. It supports a large range of bit depths from monochrome to 64-bit color. Its features include indexed color images of up to 256 colors and effective 100 percent lossless images of up to 16 bits per pixel. |
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Definition
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Definition
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Match the extension
.adf, .log, .prj workspace |
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Definition
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Definition
| Portable Network Graphics |
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Term
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Definition
Deterministic Method:
Used when set of points are dense enough to capture the full extent of surface variation. Each point has a local influence that dimishes with distance. Visually appears “bullseyed” or “pockmarked” around points. |
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Term
Interpolation Methods
Spline |
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Definition
Deterministic Method:
Used to predict smoothly varying surfaces of phenomena such as temperature. Visually appears smooth (Imagine a sheet draped over points). |
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Term
Interpolation Methods
Kriging |
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Definition
Geostatistical Method:
Used when a spatially correlated distance or directional bias in the data is known, such as in medical sciences, geochemistry or pollution modelling. Assumes the distance/direction btwn points reflects a spatial correlation that can explain the variation in a surface. Visually appears “scaled” or “layered” between points. |
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Term
Interpolation Methods
OLS Regression |
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Definition
| Requires value of all variables at all known locations & provides a global model of the variable or process you are trying to understand or predict. Visually, the most complex surface (greatest level of detail) |
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Term
| What is a geostatistical analyst output layer? |
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Definition
| pts & interpolation parameters are saved, from which the results are reproduced on-the-fly upon viewing |
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Term
| Modifiable Areal Unit Problem = MAUP |
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Definition
| When results differ after the same analysis is run on the same data with different aggregation schemes. According to ESRI’s GIS Dictionary, there are 2 forms: the scale effect (from aggregating small units into big ones) and the zone effect (from arbitrarily defined units): |
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Definition
| Assuming relationships found among aggregate units will ‘trickle down’ to the level of individuals. The assumption that an individual from a specific group or area will exhibit a trait that is predominant in the group as a whole. |
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Term
| Ecological Fallacy is exemplified in what example? |
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Definition
| BCIT works, thus, all BCIT grads work. |
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Term
| Identify and describe some issues in analysis |
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Definition
| Modifiable Areal unit Problem, Ecological Fallacy, Weighting Functions, Neighbour relationship decays with distance, defining normal spatial autocorrelation values. |
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Term
Steps to create a potential stream network with tool/function/command names not parameters
1 |
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Definition
| Take a DEM (if you don’t have one yet, the interpolation tools interpolate hydrologically correct raster from point, line, polygon data) |
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Term
Steps to create a potential stream network with tool/function/command names not parameters
2 |
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Definition
| SINK - you don’t need this step, it just shows you where the sinks are |
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Term
Steps to create a potential stream network with tool/function/command names not parameters
3 |
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Definition
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Term
Steps to create a potential stream network with tool/function/command names not parameters
4 |
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Definition
| FLOW DIRECTION - direction of flow from every cell in grid (make sure grid values of: 1,2,4,8,16,32,64,128 exist) |
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Term
Steps to create a potential stream network with tool/function/command names not parameters
5 |
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Definition
| FLOW ACCUMULATION - identities potential stream channel |
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Term
Steps to create a potential stream network with tool/function/command names not parameters
6 |
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Definition
| Reclassify flow accumulation raster to get a potential stream network (i.e. if 100 cells are flowing into its adjacent cell = 1 (stream), everything else not stream.) |
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Term
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Definition
| An environment that allows the user to graphically investigate datasets to increase their understanding. |
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Term
Methods of Exploratory Spatial Data Analysis (ESDA)
Voronoi Map |
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Definition
| Voronoi polygons are created so that every location within each polygon is closer to the sample point within that polygon, than any other sample point. |
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Term
Methods of Exploratory Spatial Data Analysis (ESDA)
Normal QQ Plot |
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Definition
| Plots input dataset against a standard normal distribution |
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Term
Methods of Exploratory Spatial Data Analysis (ESDA)
Trend Analysis |
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Definition
| Identifies trends in the input dataset. Provides a three-dimensional perspective of the data. Sample points are plotted on the x,y & z planes as scatterplots, giving a sideways view through the three-dimensional data. Polynomials are then fit through the scatterplots on the projected planes. |
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Term
Methods of Exploratory Spatial Data Analysis (ESDA)
Semivariogram/Covariance Cloud |
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Definition
| Shows the empirical semivariogram and covariance for all pairs of locations within a dataset and plots them as a function of the distance between the two locations. Used to examine the local characteristics of spatial autocorrelation within a dataset and look for local outliers. (shows variance in data, all points plotted against all points, distance on x, variance on y axis, smaller distance should show very little variance) |
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Term
Methods of Exploratory Spatial Data Analysis (ESDA)
Crosscovariance Cloud |
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Definition
| Used to examine the local characteristics of spatial correlation between two datasets, and it can be used to look for spatial shifts in correlation between two datasets. |
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Term
| Spatial autocorrelation is calculated based on two factors. What are they? |
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Definition
| Feature locations & attribute values. Given a set of features and an associated attribute, it evaluates whether the pattern expressed is clustered, dispersed, or random. |
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Term
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Definition
| The value at which a semivariogram model intersects the Y-axis |
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Term
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Definition
| The value (y-axis) where the curve of a semivarigram attains range (ie. highest point) |
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Term
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Definition
| The value(x-axis) where the curve of a semivariogram flattens out |
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