Topography

In cases where you have your own topography model, which may or may not match the one provided in a GeoModelGrid model, we recommend transforming your vertical coordinates into the GeoModelGrids model space. For example, to keep the same relative position with repsect to the model top and bottom, the \(z\) coordinate passed to the GeoModelGrids query function, \(z_query\), would be

\[z_\mathit{query} = z_\mathit{bot} + \frac{z_\mathit{user}-z_\mathit{bot}}{z_\mathit{top\_user} - z_\mathit{bot}}(z_\mathit{top} - z_\mathit{bot}),\]

where \(z_\mathit{top}\) is the elevation of the top of the GeoModelGrids model (computed using queryTopElevation()), \(z_\mathit{bot}\) is the elevation of the bottom of the GeoModelGrids model, \(z_\mathit{top\_user}\) is the elevation from your topography model, and \(z_\mathit{user}\) is the elevation you want in your query.