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 Заголовок сообщения: Forming of swamp-representing polygons on basis of strokes
СообщениеДобавлено: Ср апр 22, 2009 9:14 am 
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Vectorizing of swamp polygons is a laborious work and we tried to render it automatic even in DOS versions. Previously, a formal solution suited our customers – the program formed angular polygons via ends of strokes. They looked well enough in the scale of the source paper copy but angularity became visible at magnification.

Now (beginning with v. 8.5) the program forms quite decent smooth polygons. We have prepared a video about it, and a detail instruction will be added soon. To see the video, click here:

http://www.easytrace.com/site/russian/technology/video_list.html

Or directly here:

http://www.easytrace.com/site/russian/video/AutoSwamps/AutoSwamps.htm


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СообщениеДобавлено: Ср апр 22, 2009 9:15 am 
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Зарегистрирован: Вт мар 18, 2003 11:16 am
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Manual vectorizing of swamp polygons

The Hatched Area Outline tool is designed for semiautomatic vectorizing of swamp polygons. It first was developed for a DOS version. The tool works in black-and-white images with strokes of swamps (salt-marshes).
:!: It does not work in color sets unlike tracers.

The Hatched Area Outline tool is intended for formal reconstruction of swamp polygons – it creates segments between stroke ends + small “roofs” above the topmost and below the undermost stroke.

To vectorize a swamp polygon, cross a series of strokes. The cursor draws a rubber thread between the first and the second specified points. The program shows a polygon around the strokes you have crossed. Double click to complete the process.

If the polygon has a complex shape (X- or Y- like polygons) you may repeat the process. Come back along strokes of the already formed polygon and add remaining ones (see HELP for more details). Every crossing generates a new polygon. The polygons will be united at process completion.

:!: Unfortunately, the tool was damaged at interface alternation and worked incorrectly. We didn’t notice it at once. So it may be down in some builds.

Anyway, the tool had become actually needless when the utility for automatic vectorizing of swamps was designed.


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СообщениеДобавлено: Ср апр 22, 2009 9:16 am 
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Automatic vectorizing of swamp polygons

The utility solved two problems at once. First, it made vectorizing of swamps dozens of times faster. Second, separation of the «blue» image into «swamps» and «hydrography» accelerates vectorizing of the river net greatly. It is worth to extract and delete strokes of swamp even if you are going to export only rivers into your target GIS.

Automatic tracing of swamp polygons consists of several stages:

1. Extraction of the «blue» image. At that, integrity of strokes should be preserved as much as possible, whatever happens with other blue objects.

2. Processing of the black-and-white image. Mask filter «Swamp line extraction» + Image thinning

3. Automatic vectorizing. Autodetect Swamps utility.

4. Final editing with Eraser and Camber Editor.

5. Extraction of a normal blue image to be used for vectorizing of rivers and water bodies. Subtraction of swamp polygons from the image.

Besides swamp contours, the Autodetect Swamps utility generates an idealized model of hatching or simply recognized strokes attributed to a special vector layer. If you needn’t the polygons themselves, just imprint the strokes into the “hydrography” image to clean it.


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