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calc_areas [2011/04/20 22:36] hermann created |
calc_areas [2025/07/19 03:04] (current) admin [Notes] |
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| ===== Inputs ===== | ===== Inputs ===== | ||
| - | ^ Name ^ Type ^ Description ^ | + | ^ Name ^ Type ^ Description ^ |
| - | | Categorical Map | [[Categorical Map Type|Categorical Map ]] | Map containing classes or categories. | | + | | Source | [[Categorical Map Type|Categorical Map]] | Map whose non-null cells correspond to categories or classes. | |
| + | | Use Authalic Area | [[Boolean Value Type|Boolean Value]] | If set to true, the area of each cell in a geographic grid (Lat/Long) is computed using an authalic sphere, which preserves surface area during projection. This improves the accuracy of area calculations across all latitudes by avoiding distortions in geographic coordinate systems. If the grid is geographic but the flag is set to false, all cells are treated as having the same area, calculated by treating the length of one degree of latitude or longitude as a constant 111255 meters. | | ||
| ===== Output ===== | ===== Output ===== | ||
| - | ^ Name ^ Type ^ Description ^ | + | ^ Name ^ Type ^ Description ^ |
| - | | Areas | [[Lookup Table Type|Lookup Table ]] | Table containing the areas for each map category. | | + | | Areas | [[Table Type|Table]] | Area of each map category in cells, hectares and square meters. | |
| ===== Group ===== | ===== Group ===== | ||
| - | Map Algebra | + | [[Functor List#Map Algebra|Map Algebra]] |
| ===== Notes ===== | ===== Notes ===== | ||
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| Only the areas corresponding to class or categories defined in the input map header are calculated. | Only the areas corresponding to class or categories defined in the input map header are calculated. | ||
| + | The table containing the resulting area has the following format. | ||
| + | |||
| + | ^ Column Name ^ Key or Data? ^ Column Type ^ Description ^ | ||
| + | | "Category" | Key | Real | Category in the feature map | | ||
| + | | "Area_In_Cells" | Data | Real | Area of corresponding category in cells | | ||
| + | | "Area_In_Hectares" | Data | Real | Area of corresponding category in hectares | | ||
| + | | "Area_In_Square_Meters" | Data | Real | Area of corresponding category in square meters | | ||
| ===== Internal Name ===== | ===== Internal Name ===== | ||
| CalcAreas | CalcAreas | ||