[Theme] elevation contour only

[barbudor]

Hello

Does anyone knows about an on-line map source for transparent elevation contour lines that could be used as an overlay over satellite imagery maps ?

I am looking to achieve something like in Strava (see below) by adding elevation contour on-top of Google or others satellite  maps.

Thanks in advance

best regards

barbudor

[john_percy]

It would be quite easy to do that with a custom theme for an offline vector map.

In the screenshot below, the overlay map is an appropriate vector map, the theme is contours (attached). Blend mode is SRC_OVER.

Both Locus Maps and OpenAndroMaps maps have contour lines with height marked for major intervals.



Updated upload

[Menion]

Thanks @john_percy! My suggestion may be exactly same, there is probably no better solution (at least I'm not aware of any better).

[barbudor]

Hi John

Thanks, it's working great.

I am not yet much aware about XML theme files.
I would like to try to make the lines more visibles.
What should I look for in the XML file (color, thickness, ...) ?

It would be great if I could make the countour line as a pair of black+white lines side by side to increase the contrast.

If you know a good place to learn about tweaking XML files, that would me much appreciated.

EDIT : Question : There are 2 contoursxml files in the ZIP. Is that normal ? Shall I keep both ?


Thanks a lot

Best regards

Barbudor

[barbudor]

@Menion

I am trying to use this over offline map too.
It appears that sqlitedb files supports overlay but rmap doesn't.
Both have been made by MobAC.

Thanks

[john_percy]

I am not yet much aware about XML theme files.
I would like to try to make the lines more visibles.
What should I look for in the XML file (color, thickness, ...) ?
It would be great if I could make the contour line as a pair of black+white lines side by side to increase the contrast.

I'm sorry about the two contour.xml files in the zip. My fault. I've now uploaded a corrected zipfile in my previous post above.
The lines are a very pale green with a grey outline.
The colours are defined by

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stroke="#4A5255" and

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stroke="#B5C7A1 and

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fill="#B5C7A1" Two colours appearing several times. You can do a global search and replace: for example, #FFFFFF would be white and #000000 would be black.

The thickness is defined by

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stroke-width="1.4dp" with various thicknesses for differing zoom levels. That needs approaching with some care, seeing what gives you the look you want.

[Menion]

It appears that sqlitedb files supports overlay but rmap doesn't.

Correct. That's how it's done.

[barbudor]

@John

Many thanks. I'll experiment with this.

@Menion

Ok. I was moving more to rmap because I can share the same file between Locus and desktop CompeGPSLand application.

Many thanks.

Best regards

[gynta]

It would be quite easy to do that with a custom theme for an offline vector map

@john_percy
Hi John
' don't know why - but this theme doesn't work for me.

any ideas?

[john_percy]

It's not working properly for me now. Zooming in or out results in incorrect segments of contour lines on the map.
If you choose the theme again, it redraws correctly. So it's some kind of bug?

[john_percy]

The problem I find is connected to the rendering of the transparency of the fill defined in the theme. Used as a theme on its own, contours is rendered with spurious segments of contours when the zoom level is changed.
However, it seems to work as an overlay:
1. Select a non-vector map as the base
2. Select a vector map as the overlay
3. Blend=disabled, etc
4. Select contours as the theme
5. Zoom in and out.

As an alternative, set the background fill in the contours theme to #FFFFFF, and the blend to multiply in the overlay. That way the theme works as a standalone map and as an overlay.

I attach a slightly simplified theme as well as an opaque version.