I think you have run into the issue of Transparency Acne, which is when the rendering engine identifies two pixels from overlying and underlying sheets as being the same colour and therefore a pinprick hole in the topmost sheet. This would be harmless, except for the sheet effects on the topmost sheet. Edge Fade, Inner sheet effects, and both bevel effects are affected by this, and produce a tidy hole or dimple around the edge of the pinprick as if it was a real hole in the polygon.

With this style the easiest solution is to add a new sheet between the two existing grassy textures and copy the polygons from the topmost sheet onto it, then turn those new polygons on the new sheet a solid colour that is least likely to be in the topmost texture. Then copy the Edge Fade Inner sheet effect from the top sheet to the new 'backing sheet' and tweak the values up just a little to prevent it from showing around the edges.

It was your thread that gave me the initial idea to do this :)

It works ok if you use the correctional displacements after the main one. One red and one green. They are just 500 px bitmaps of pure red and pure green.

There's no rhyme or reason to the actual amount each will be required, but at a scale of 500 I needed a displacement value of anywhere between 0.2 and 3.0, depending on how bad the drift was. Using the same values in both green and red correction displacements to start with helped a lot, otherwise it is a bit like trying to saw just the right amount off the legs of a rocky table without a tape measure.

I will try that, Joe - Thanks very much for taking the time to create it.

I found a way around it by playing with a red png and a green png for adjustment.

This shot shows the shift happening with just the displace I was using before, a little exaggerated to make it clear.

This is with the plain red png distort

And this is with the plain green distort.

I am thinking that my normal map might be at fault somehow, so this is your normal map without the extra adjusting distorts

And then again with them (though I had to increase the Displacemet amount on the correction effects by a factor of 3 to make it go right for your normal map). It's a bit like using the Displace to move the whole thing back on x and y axis separately, but I guess that's quite an accurate description if the 'normal' maps I'm using are just two plates of solid colour.

Here are the adjustment pngs I was using - one green, and one red.

Great map :)

It would almost be worth turning the grid at an angle to match the diagonal nature of the building.

Hi Everyone! :D

In this week's Live Mapping session Ralf will be creating and using heraldic symbols from the March issue of the 2008 Cartographer's Annual.

Come along and join in the fun :)