06/09/2011

Calculate area by QGIS


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Mengitung keluasan dengan QGIS

Field calculator merupakan alat untuk menghitungkan keluasan polygon secara automatik dimana expression adalah $area. Hasil pengihtungan menggunakan filed calculator bukan dalam unit hectare dan adalah dalam unit sq.metre hanya sebab dikonfigur pengukurannya dalam metre dan bukan feet. Ini bermakna sekiranya pengguna ingin mendapatkan hasil dalam unit hectare, perlu dilakukan tindakan tambahan untuk convert unit sq.metre ke hectare. Formulanya adalah 1/10,000 bagi unit hectare. Ini akan ubahkan hasil calculation asal secara automatik dari sq.metre ke hectare. Kami buat semakan Google search dan dapati ramai yang tidak tahu cara untuk calculate area by QGIS, oleh itu, mereka menyangka QGIS tidak boleh menghasilkan output tersebut tetapi sebenarnya QGIS boleh dan hanya memerlukan simple conversion mathematics. Kesimpulannya jangan percaya semua yang dinyatakan dalam Internet, perlulah pengguna buat sedikit trial & error.

Calculate area by QGIS

The Field calculator represents the tool for automatically calculating the area of a polygon where the expression is $area. The result of the calculation using the Field Calculator is not in unit hectare but in unit s. metre only because I had set the measurement to be in metres and not feet. This means that if the user needs to calculate in hectare unit, there is a need to do additional calculation to convert the sq. metre to hectare. The formula is 1/10,000 per hectare unit. This is automatically convert the result of the original calculation from sg. metre to hectare. We did a check on Google search and found out that not many know how to calculate are using QGIS and as such they presume QGIS cannot produce the needed output while it actually can and only requires simple mathematics conversion. The conclusion is do not believe everything you read on the Internet, there is a need to do some trial and error.

2 comments:

  1. it's work..but sir could u tech me how to made a topology editing in QGIS for a shapefile data from ArcGIS??actually in a baby in a box with QGIS..

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  2. You exploit GRASS editing modules here:-D Basically first you create a GRASS mapset then import your .shp file there then open GRASS tools and select whichever vector modules for cleaning you prefer the output needs to be exported to .shp if you intend to use it later as a .shp file. I would appreciate if you register here as a member then I know whom to address to because there are many Anonymous. Thanks.

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