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I would implement the solution that is describe here Geometry based automatic fill of fields in attribute table The solution is essentially a trigger that will update the field automatically when ever a transaction occurs. This way, the data will not only populate the field upon data creation, but also if geometry changes. I would also move off of using a ...


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I wrote a example and it seams to works fine. I used project4 to transform UTM coordinates to EPSG3854(Openlayer default projection) function utm2EPSG3857(point, zone) { const utm = "+proj=utm +zone=" + zone; const target = "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext ...


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You are wrong to assume that 1 grid cell (pixel) side is 1 meter in UTM or any other coordinate reference system. It can be anything (up to ~600 km for a single column raster, if you want to stay within UTM zone boundaries). It is also important to note that cell size is not constant. With a longitude/latitude coordinate reference system (CRS), I assume that ...


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I ended up using the Intersection feature in Processing -> Toolbox -> Vector overlay to identify the area of overlap of the two shapefiles. Then, using the resulting shapefile, I went to the Attributes table -> Open Field Calculator and created a new field using $area. With this I got the area of each polygon which I ended up exporting as a csv ...


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In QGIS, when you set the CRS, there is a window t the bottom that shows the WKT version of the CRS, and the Proj version. It contains the length unit. The area is the square of that. For South America Albers Equal Area Conic (ESRI 102033), for example, it is: WKT PROJCRS["South_America_Albers_Equal_Area_Conic", BASEGEOGCRS["SAD69", ...


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Get area using dplyr::mutate and sf::st_area library(sf); library(dplyr) p <- st_read("polygon.shp") p %>% mutate(crown_area_m2 = as.integer(st_area(p))) or simply p %>% mutate(crown_area_m2 = st_area(p))


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A relative simple solution would involve these steps: On the layer in Web Mercator projection (EPSG:3857), create a new attribute with field calculator, calclulating the area distortion of each polygon: divide the distorted area by the "real" area. The distorted area can simply be calculated with area($geometry) (planimetric calculation). The real ...


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