RSF Workflow

[benscarlson]

Hello,

I'm attempting to use amt in the typical create random points/extract covariates workflow, but I'm running into some problems. I'm not sure if this is the right place to post questions but here goes.

dat <- read_csv('my_data.csv',col_types=cols()) #x,y data for rsf, in lon/lat
rast <- raster('my_layer.tif') #also lon/lat, epsg:4326

The most straightforward approach is to do the following

 dat %>% 
  make_track(lon,lat,crs = CRS('+init=epsg:4326')) %>%
  random_points %>%
  extract_covariates(rast)

This works but this gives me warning messages (below). I assume because random_points uses sf internally, which doesn't work as well with spherical coordinates.

although coordinates are longitude/latitude, st_intersects assumes that they are planar

Converting to a flat projection then seems to require a fairly convoluted workflow to extract covariates. In addition, the random points object needs to be a spatial object in order to transform coordinates, but using make_track drops the case_ column.

dat %>% 
  make_track(lon,lat,crs = CRS('+init=epsg:4326')) %>%
  transform_coords(CRS('+init=epsg:3035')) %>%
  random_points %>%
  make_track(x_,y_,crs = CRS('+init=epsg:3035')) %>%
  transform_coords('+init=epsg:4326') %>%
  extract_covariates(rast)

• It might be nice if random_points could accept a bounding box (or any polygon) in the coordinates system that matches the tracks, instead of forcing mcp or kde.
• Also it might be nice if random points was a spatial object, such as an sf object, so that it's easy to do transformations on the points.
• Is there a good way to tell make_track to keep all the columns in the data frame? There might be but I can't figure it out.
• Finally, it would be nice if extract_covariates converted to the coordinate system of the raster before doing extraction. This is what raster::extract usually does, and I see in the code that extract_covariates is internally using raster::extract, but if using amt I have to explicitly do the conversion.

Thank you for the help!

Ben