Is there a process for initializing costmaps from DEM?

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I am looking for a process or set of steps to initialize costmap2d, grid_map or octomap from DEM and feature data provided apriori from an external source (e.g. USGS). Does anyone have a guide or walkthrough on how they performed this? I need to build some initial, geospatially referenced map layers before adding occupancy map layers and other cost map layer values. I found information for sucking DEM into Gazebo but I need to suck the DEM data into the cost map data and use it as part of the planning solution and navigation solution algorithms. Anything would be great. DEM = Digital Elevation Model - aka DTED