#Help text for tool "D-Infinity Distance Up".
URL
https://hydrology.usu.edu/taudem/taudem5/help53/dinfinitydistanceup.html
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TEXT
<p>This tool calculates the distance from each grid cell up to the ridge cells along the reverse D-infinity flow directions. Ridge cells are defined to be grid cells that have no contribution from grid cells further upslope. Given the convergence of multiple flow paths at any grid cell, any given grid cell can have multiple upslope ridge cells. There are three statictical methods that this tool can use: maximum distance, minimum distance and weighted flow average over these flow paths. A variant on the above is to consider only grid cells that contribute flow with a proportion greater than a user specified threshold (t) to be considered as upslope of any given grid cell. Setting t=0.5 would result in only one flow path from any grid cell and would give the result equivalent to a D8 flow model, rather than D-infinity flow model, where flow is proportioned between two downslope grid cells. There are several different options for the way distance can be measured: the total straight line path (Pythagoras), the horizontal component of the straight line path, the vertical component of the straight line path, or the total surface flow path. In the case of grids in a projected coordinate system, no unit conversions are done and the units are map units.  Horizontal distances will be in the  units of the grid cells and vertical distances in the units of the input elevation grid (fel). If these are inconsistent, then results will be incorrect for the case of mixed vertical and horizontal distances (Pythagoras, surface). In the case of grids in geograhic coordinates, a WGS84 spheroid is used to convert decimal degree cell sizes into meters for the computation of horizontal distances. Vertical distances remain in the units of the input elevation grid (fel), and mixed vertical and horizontal distances will be incorrect unless the vertical units are meters.</p>
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