# Tag Info

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If you have 3D Analyst, this works - for individual polygons: Create a TIN using your polygon Use Add Surface Information with your polygon as input feature class and the corresponding TIN as input surface. Check "SURFACE_AREA" as output property. The 3D area is then added in a new field to your polygon feature class' attribute table. You can automate ...

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As an alternative approach, you could rasterize your polygon mangrove layer (assign pixels corresponding to mangrove polygons as 1 and everything else 0) and then use the Raster >Zonal Statistics algorithm to calculate both the "sum" and "count" statistics within each grid square. Zonal Statistics will append the values to the square grids and then you can ...

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This answer on a question with a similar theme may provide an explanation for your observation: ..since your data is in Decimal Degrees, you will not be able to perform a linear calculation for the true area of your raster cells. Since the lines of Longitude converge at the Poles, the distance represented by 1 degree of Longitude decreases as you ...

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You removed the checkbox for geodesic measure and the list for the type of geometry from your HTML but they are still used in your JS like here for example : var typeSelect = document.getElementById('type'); var geodesicCheckbox = document.getElementById('geodesic'); you'll need to take off all these lines and every call to these 2 variables from your ...

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Try out: UPDATE table_1 SET area = XXX FROM (SELECT ST_Area((ST_Within(table_2.geom, table_1.geom))) AS XXX from table_2 or more where conditions) mysubquery; I had same problem, but I solved it in this way.

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You have several issues with your query. First: ST_Within only returns true or false, no geometry. ST_Intersection will give you the intersecting geometries(the portions you want to have). Also the syntax of SET is wrong (SET is also no constraint, try to read some database basics, and also in the documentaion are several examples). Second: You are trying ...

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If I understand your question correctly, this UPDATE statement will do what you want: UPDATE table_1 -- For each row in table_1... SET area = ( -- set its area... SELECT SUM(ST_Area(table_2.geom)) -- to the sum of the areas of the geometries... FROM table_2 -- of table 2... WHERE ...

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I've found similar issues when adding polygons and updating an area field with (\$area/10000). It uses a different method than (area(\$geometry)) and often returns a different answer. I've concluded that editing, saving edits, turn editing off, open table/recalc field with (area(\$geometry)) works consistently. I don't mind discrepancies and errors, as I ...

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You can do library(raster) x <- shapefile('file.shp') crs(x) x\$area_sqkm <- area(x) / 1000000 Assuming that your crs is longitude/latitude, or with meter as distance unit

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Since you're only interested in areas where WPC is greater than 3, you can start by creating a subset of your wind potential shapefile which only contains polygons where this is true. Go to Insert > Select By Attributes, ensure your wind potential shapefile is selected, then create a query to select where "WPC > 3." Click OK, and those polygons should be ...

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This was merely a stupid mistake. My app's code wasn't updating the place's point column being used in the query and the data in the point query wasn't actually near London. So I thought I was setting the points close to London, but it wasn't really doing it!

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The reason that your current query is not returning anything is because you do not have the data there to complete the query that you want. I think that you are heading in the right direction, but you will need to have more data in your places table to properly realise the way the query will behave. You stated in your comments that you want to you want to ...

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If I understand what you are trying to do, you don't need to dissolve, you just need to summarize by landscape zone after intersecting the two datasets. If you do this in a geodatabase the area of each polygon is calculated when the intersection is completed.

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