Contents
How do you Reproject a DEM?
To reproject a DEM, setup a project with the desired projection (CatchmentSIM Drop Down >> New Project), setup the DEM with the desired boundaries and resolution (Create DEM >> Setup Blank DEM) and then populate the DEM pixel elevations with the external DEM (Create DEM >> Raster DEM).
How do you Reproject a DEM in Arcmap?
To reproject data, use the Project Raster tool. In ArcCatalog or the Catalog window, right-click the raster whose coordinate system you want to define and click Properties. Scroll down to the Spatial Reference section, and click Edit.
How do I change my Dem coordinate system?
Right-click a DEM file in the Prospector list view and click Properties. In the DEM File Properties dialog box, select the CS Code property field and click the browse button. In the Select Coordinate Zone dialog box, click the Category list and select a category. Select a coordinate system from the category list.
How to calculate the slope of the dem?
Compute the slope of the projected DEM either as a pure slope or a percent ( not as an angle). Divide this slope by the projected cosine (latitude) grid. If desired, reproject the slope grid to any other coordinate system for further analysis or mapping.
How to calculate the slope of a grid?
Compute the slope (as rise:run or a percent) using a Mercator projection, then divide the result by the cosine of the latitude. To do this with a grid given in decimal degrees (such as an SRTM DEM), perform the following steps: Create a latitude grid.
How to calculate the Dem of a latitude grid?
To do this with a grid given in decimal degrees (such as an SRTM DEM), perform the following steps: Create a latitude grid. (This is just the y-coordinate grid.) Compute its cosine. Project both the DEM and the cosine of the latitude using a Mercator projection in which scale is true at the Equator.
How is the slope of a Mercator projection calculated?
The Mercator projection fits the bill: assuming scale is correct at the Equator, its distortion equals the secant of the latitude. That is, distances on the map appear to be multiplied by the secant. This causes any slope calculation to compute rise: (sec (f)*run) (which is a ratio), where f is the latitude.