Autor Thema: old paper maps to raster shaded relief  (Gelesen 3861 mal)

Offline daves

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old paper maps to raster shaded relief
« am: 21 Oktober 2015, 18:41:31 »
is there a how to instruction
 or can someone post the steps on how to take old paper DNR map and make it available to display on HDS?
I have multiple  old maps and charts from a specific trout fishing area I would like to change to raster to display on hds
when I tried with imc  only parts of the map display ...I am probably missing one little step but for the moment im stumped
any help is appreciated ds

Offline gregory

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Re: old paper maps to raster shaded relief
« Antwort #1 am: 21 Oktober 2015, 19:15:44 »
What do you mean by "only parts of the map display"?

If only the edges are being cut off the image, you might need to turn off the "Filter Alpha" option.

Offline Hubert

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Re: old paper maps to raster shaded relief
« Antwort #2 am: 22 Oktober 2015, 09:27:49 »
A little work, but shoud be the best way in my opinion:

Make a scan or photo of your map, import it into Google Earth and place it on the right place.
After that you could redraw your depth lines (and other parts, if you like) in Google Earth and save each line separate. Now you can import these lines into Reefmaster and set the correct depth values (or use them just as markerlines).

Gruß vom Chiemsee ;)
Boot Marine 450 Fish, Motorguide Xi5-55FW, Golden Motor 15 (E-Motor), Suzuki DF 30 ATHL

Offline daves

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    • My/Mein Tackle Equipment: walleye fresh water
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Re: old paper maps to raster shaded relief
« Antwort #3 am: 25 Oktober 2015, 23:11:32 »
greg
 here is a screen pic with alpha selected and deselected
  one the maps will display but large black border...
the second it cuts off most of the raster map only a small portion of the map can be seen

I am trying to build  multiple raster images ......10  maps in a relatively close area approx. 40 miles
I edited the images to have a transparent background  so I could georeference them in GE then to kml...then imc keyhole and finally all edited files in one folder to run thru imc raster mode
suggestions?
ds

Offline gregory

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Re: old paper maps to raster shaded relief
« Antwort #4 am: 26 Oktober 2015, 02:03:03 »
The Filter Alpha is very much like doing surgery with a chainsaw.  It checks to see if the requisite number of pixels are set and uses that to determine whether or not to cut off the block.

The black background image is an unfortunate reality but there's some things you can do to cleanly remove it but it gets more complicated.

What I would recommend doing is finding some imagery to use a background map.  You can use OSM Raster Tiles, for instance.  The source data can be anything as it's just being used to replace the black and give you a point of reference.  You want to make sure that they cover your region up to the extents of the data you care about.

If you get a suitable boundary around the data, you can use the Filter Alpha option, the extents options, or the Filter Shapefile option.

Extents allows you to specify the outer extents of where you want the raster data to appear on the card.  This would be in the same projection as your source.

Filter Shapefile allows you to provide the exact location of your outputted raster files as polygon vector data in a shapefile.