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Hi there,

i am trying to calculate area of whole bunch of vertical standing free form 3d Polygons but somehow the calculated areas (sloped area) are not correct, for instance a polygon that suppose to have 35m2 area (calculated in autocad), gets here a 18m2 area in FME!

i import a dwg with closed 3d polygons in FME and then i use "Area Calculator" with Sloped surface option and multiplication factor 1. the units area in meters...

does it sound familiar to anyone and is there any solution to it? any help would be appreciated.

 

Hi @fma,

I haven't seen this problem before. Would you mind posting a sample of your polygons so that we can test FME on them?

Hi @fma,

I haven't seen this problem before. Would you mind posting a sample of your polygons so that we can test FME on them?

Ha Dave,

Thanks for your reply. i'll put a dwg source file and FME model and the resulted shapefile in the attachements.

how i noticed is that if i convert the 3d polylines in Autocad into surfpatch and then calculate area with Area command, then the result is different from the number in field Area in converted shapefile from FME.

Looking forward to see your response on this soon and whether or not this can be fixed.

Convert_dwg_shp.zip

Load_Repair.fmw

Test_Repair_spots.dwg

thanks in advance.

Hi @fma,

Thank you for the files.

The AreaCalculator will only give a valid answer for 3D polygons which are planar. But you can get a better answer calculating the area of non-planar 3D faces. To convert your polygons to faces, please use a FaceReplacer, with Thickness Mode and Angular mode set to Ignore.

Hi @fma,

Thank you for the files.

The AreaCalculator will only give a valid answer for 3D polygons which are planar. But you can get a better answer calculating the area of non-planar 3D faces. To convert your polygons to faces, please use a FaceReplacer, with Thickness Mode and Angular mode set to Ignore.

Thanks Dave for tip. i tried and it works fine for more than 95% of the surfaces, but i see some cases that 3dface area is about 40% higher than actually is, these are surfaces with inward folds that are probably seen as an one big surface i guess... if there is a workaround that, i would be happy to try. anyway thanks so far. it's been a great help.

Thanks Dave for tip. i tried and it works fine for more than 95% of the surfaces, but i see some cases that 3dface area is about 40% higher than actually is, these are surfaces with inward folds that are probably seen as an one big surface i guess... if there is a workaround that, i would be happy to try. anyway thanks so far. it's been a great help.

Hi @fma,

You may get better results with curved faces if you send the faces to a Triangulator, then calculate the area of the TINSurface output.

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