Activities

Ancient Lake Algonquin. Ten thousand years ago the northern Michigan shoreline was much different than it is today. Digital analysis of terrain survey data employing global positioning systems (GPS) and baseline elevation data, we can reconstruct the boundaries of this ancient lake and better understand the region's dynamic past.

Land Surface Change Monitoring. Dynamic terrain like dune fields can change rapidly. This map shows the results of a process quantifying the extent of this change between two high-resolution elevation models.

Multiresolution data models. Here a regularly gridded dataset is partitioned into regions of variable interpolation error based on a recursive compression algorithm. The partition can assist in identifying areas that are difficult to model, or inform appropriate remediation.

Fuzzy classification models. Classification maps can include varibles that exhibit non-discrete boundaries. Here, fuzzy set theory is used to develop more realistic representations.

Error Propagation via Monte Carlo simulation. A process is detailed in this diagram to determine the effect of input spatial data error on a GIS operation. We have investigated a variety of different components for this process.

Characterizing spatial data error. Here, red indicates elevations that are higher than actual, and blue indicates elevations that are lower. We can use maps like this to model error pattern.

Modeling spatial distribution of grain prices in West Africa. Advanced statistical techniques can be used to identify spatial pattern. Such patterns may inform policy and management decisions for the region.

Alternative global data models. The earth is not a plane. What are the implications for using a model like this to characterize global data sets?

Compact Spatial Data Models. The DEM shown here consists of 4,096 different elevations. Employing a flexible discrete cosine transform alllows us to characterize the surface with only a few coefficients. The red contours represent a surface with 64, 32, 16, 8, and 4 coefficients, respectively.

Geometric Probability. The use of spatial partitions in a data set implies that some features will intersect multiple tiles. Here the probability of such intersections is analyzed for equilateral triangular tiles

Choice of raster cell resolution affects what can be observed; this is linked in complex ways to the process scale of the mapped vector phenomenon. Here we see the impact of different resolutions on land cover data.