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# GIS Analysis Quiz1

### Surface Quiz for COCC GEOG 287

Question | Answer |
---|---|

What is a surface? | A continuous field of values that may vary over an infinite number of points |

What are some Discrete Surfaces? | *Dot Distribution *Proportional Symbols *Choropleth *Isarithmic |

What are the methods for creating Raster Surfaces? | Interpolation *Inverse Distance Weighted *Trend Surface *Spine *Kriging |

What are the methods for creating Vector Surfaces? | Triangulation *TIN |

How does TIN work? | Constructed by triangulating vertices which are connected in a series of edges to form a network of triangles. |

What is Delaunay Criteria? | No vertex lies within the interior of any of the circumcircles of the triangles in the network. |

Drawbacks of TIN surfaces? | * Less available * Tend to cost more to build and process |

What is Interpolation? | Estimating unknown values that fall between known values |

What is Linear Interpolation? | Common Slope, most basic interpolation, assumes a linear line |

What is Inverse Distance Weighting (IDW)? | Sample points closer to the cell have a greater influence on the cell's estimated value than sample points that are farther away |

What are some traits of IDW? | *Will not exceed or pass through points *A points influence on the kernel is weighted by the square of the distance from the kernel |

What is Spline Interpolation? | Spline interpolation method fits a flexible surface through the known value locations |

What are some traits of Splining? | *Through each sample point and may exceed the value range of the sample point set. |

What is Trend Surface Interpolation? | “Best-fit” based on mathematical equation, uses orders i.g. 1st order, 2nd order, 3rd order to determine best fit. |

What is Kriging Interpolation? | Is an advanced geostatistical procedure that generates an estimated surface from a scattered set of points with z-values based on statistical models that include autocorrelation. |

Describe the elements of a Semivariogram? | *Sill- The Y- peak where the data levels out * Range - The X value where the peak of the data is *Nugget Variance - The Y Intercept (where the value crosses the Y axis) |

What are some problems with Interpolation? | *Number of sample points can limit accuracy *Location of sample points may not represent population *Saddle points *Don't extrapolate |

What is Dasymetric Mapping? | Mapping depicts quantitative areal data using boundaries that divide the area into zones of relative homogeneity with the purpose of better portraying the underlying distribution. *GIS does not have this capability, yet |

Created by:
Sevcav