# Extract footprint from mass

Im trying to implement a method which can easily show the footprint of a mass. The revit mass dynamically updates gross floor area, but not footprint, so i attempted at a graph that would do so.

The graph takes all surfaces from the geometry, filters surfaces that have a normal vector of 0 to account for sloped surfaces.

After this i am sort of stuck. I wish to project the surfaces to a plane, merge them, and extract the area of the new surface. However i could not find nodes that would facilitate this workflow.

Abother attempt was to extract the curves of the surface, project them to a plane, eliminate coinciding curves to create a boundary, surface by patch it. Howver again i could not find a way to eliminate coinciding curves.

If anyone has experience with footprint extraction of geometries, i would appreciate some tips and assistance.

Here is one of the possible way to get mass bottom surface.

@Tchunoo_Rhee_Kahng Ensure there is a level at the base of the mass and a corresponding Mass Floor, you can then do something like thisâ€¦

Also, the nodes in your screen shots abbove arenâ€™t clear. zoom in until the text in the nodes is visible before you capture the screen in Dynamo. The entire graph is captured even if it isnâ€™t visible on your screen.

thanks for the response guys!! I believe i have not articulated my question. I want to figure out the Building Coverage of a mass with a â€śFootprint(touching GL)â€ť is not equal to the Projected Boundary in Site Plan.

So i just want to find the â€śSite Coverageâ€ť of a Mass.

and @Vikram_Subbaiah thanks for the tip on screen shots, I always wondered why my caps were so fuzzy.

I hope this can clear up some confusion.

Hello, this outer boundary method could probably help: Get an outer boundary of multiple polygons (Room Boundaries)

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@Tchunoo_Kahng My above suggestion should work. Assuming Level 1 is footprint level, extract the mass Floor Area of Level 1
In the example below the base of each block is 100sqm, the resulting Mass Floor Area parameter reads 200sqm