Hi Sandy! My thoughts on the matter:
The reason for creating different layers like you have seen may be that the data originates from different sources, or represent different degrees of resolution. The large scale polygons may be the result of large scale 'desktop' mapping, while smaller polygons may come from observations in the field. Other than that, I see no reason to store data in different tables based on polygon size, or the fact that some geometries overlap others. Maybe the software that was used had problems creating islands and lakes (donut shapes), so one solution was to separate them to at least be able to plot a properly looking map. But of course, area calculations will come out wrong. I would strongly suggest that data of the same kind be kept in the same table or layer, no matter what the polygon sizes are. Lakes and islands should be treated as separate entities, not part of their surrounding areas. Hälsning / Best regards Mats.E ________________________ FB Engineering AB Södra Förstadsgatan 26 211 43 Malmö Tel: 040-660 25 50 Mobil: 0705-27 60 27 Fax: 040-660 25 99 [EMAIL PROTECTED] www.fbe.se [EMAIL PROTECTED] 2005-06-28 06:55 Till [email protected] Kopia Ärende MI-L polygon creation philosophy There appear to be two end members on how to create geologic map polygons. One is to create a single layer that contains separate polygons for every formation/ outcrop/ zone (no matter the size). The other is to create a series of layers that contain polygons of various sizes. One layer would contain broad/large scale polygons while other layers would contain detailed polygons that would appear to be within the larger polygon [but not digitized as an island or lake]. I have seen both styles used. Is one method technically better than the other or is the method choice dependent on what the end use will be? what do the members of this list prefer? sandy figuers norfleet consultants
