[mkgmap-dev] combining two img covering other polygon belowFrom Adrian ar2988-os at yahoo.co.uk on Fri Nov 12 23:01:03 GMT 2010
On 11/11/2010, maning sambale wrote: > The problem, all other polygons and lines are "under" the contour > polys including the boundingbox of the test contour map. POIS and > labels are visible. I see you are using RoadTrip on Mac. Your map has a white background. Therefore you will have specified a land polygon type in the style file, and you will have set that polygon type to white with a .TYP file. What you are seeing is the white background of your contour overlay map, covering the road map below. The labels are visible because of a bug in RoadTrip. Mapsource is similar. In a Garmin map, pixels can only be 100% transparent or 100% opaque. You cannot have partial transparency - you cannot blend two colours. This is because many Garmin devices have a palette of only 256 colours. You need to have different processing of the base map and the overlay map, so that only one has a white background. This will only partly solve the problem, however, because you have applied colours to areas above a certain height. These coloured areas will still cover the map below. You have three options: 1. Accept that the coloured areas will cover the map below. 2. Have the contour layer below, with a white background, and the road layer above, transparent with no background. Then you have to accept that areas in the road map, such as woods and lakes, will cover the coloured areas in the contour layer. 3. You could experiment with a stipple (a mixture of transparent and opaque pixels) for the colour in the contour layer, so that some of the map detail below will show through, and see if you can get a satisfactory result. I have successfully produced maps with a road map layer below, and a transparent contour layer above, using standard Garmin line types for the contours. These maps display correctly on the GPS device. But Mapsource and RoadTrip do not display these maps correctly because of a bug. The contours are covered by some of the areas in the map. You may know how to control which map is above, and which is below, both in Mapsource and on the GPS device. If not, these may help: http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2009q4/006026.html http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2010q1/006746.html There is a more detailed description somewhere but I could not find it when I looked just now. Perhaps someone could kindly point us towards it? For above and below, RoadTrip behaves similarly to Mapsource.
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