Basically, I have points on the map with $ values, as well as polygons showing areas of risk.
I want to create a 20km by 20km grid over my map, and summarise the total $ value of all points within each square, and the percentage of the square that is taken up by the risk polygons.
Can someone please advise if this is possible in ArcGIS Pro, and what tool you would use to create the grid?
or Spatial Join plus other options, depends on what your data are like and what you need to summarize
Thanks for that!
I need to set the grid squares at 20km squared - I wasn't able to find what the cell height and width referred to as anything that I entered over 1 was bigger than the map area that was looking at (State of Victoria, Australia - which I have a polygon for) and didn't have the option to change to metres / km or even see what the standard measurement is.
I tried the Generate Tessellation tool and it has the option to select the shape type as square and size which I was able to select as square kilometres, however when I do this I get the following warning: 'WARNING Converting areal units squaremeters to squareunknown not supported.'
Any suggestions would be great!!
It sounds like you might be working with Geographic Coordinates (aka decimal degree data), or worse... an unknown coordinate system.
Make sure you map is set to a projected coordinate system suitable for your area.... anything other than web Mercator …
at some stage you are going to have to specify a Projected coordinate system in order to get planar areas
and similar approach when using Fishnet
Make sure you map is set to a projected coordinate system suitable for your area
The map is not what needs to be projected - the coordinate system used for the geoprocessing must be set to a projected coordinate system (ie UTM, Australian National Grid, whatever) where the units are meters (NOT degrees).
Melissa, your best bet is to use the Project tool to convert your points and polygons to an appropriate projected coordinate system and generate the fishnet using one of those datasets that covers the study area to define the extent. Here's an example coordinate system: GDA94 / Vicgrid94: EPSG Projection -- Spatial Reference (WKID 3111)
A projected coordinate system like the one suggested, has the units of meters, hence area will be in m^2, which can be displayed and/or calculated to km^2.
Have you tried projecting the polygon grid? the Shape_Area field will be in m^2... easy conversion from there
Melissa, I suggested one optimized for Victoria that has xy units of meters. With the fishnet tool, provide a grid cell size in meters, ie 20000 for 20 km polygon grid cells.