Comments on: Reuse and Prosper http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/ Notes From A Strange Place Wed, 08 Sep 2010 10:03:04 +0100 http://wordpress.org/?v=2.8.6 hourly 1 By: Andy http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/comment-page-1/#comment-28336 Andy Mon, 24 Dec 2007 12:23:31 +0000 http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/#comment-28336 The secret is that every semi-transparent line needs to be drawn with no transparency to a buffer before the entire lot is applied with alpha-blending to the rest of the image. It's the only way to avoid additive transparency where they overlap. Doing this for the cycle map involved getting a new API for the rendering tool (mapnik) - each section of the map is drawn to around six different buffer images (background, lcn, rcn, ncn, overlay and a couple of others) which are finally overlaid on each other with the appropriate transparency. I doubt that the Google API (or anything else, for that matter) will let you stroke each line to a buffer before applying transparency in one go - almost everything will draw each line semi-transparently one line at a time, which leads to the overlap problems. The secret is that every semi-transparent line needs to be drawn with no transparency to a buffer before the entire lot is applied with alpha-blending to the rest of the image. It’s the only way to avoid additive transparency where they overlap. Doing this for the cycle map involved getting a new API for the rendering tool (mapnik) – each section of the map is drawn to around six different buffer images (background, lcn, rcn, ncn, overlay and a couple of others) which are finally overlaid on each other with the appropriate transparency.

I doubt that the Google API (or anything else, for that matter) will let you stroke each line to a buffer before applying transparency in one go – almost everything will draw each line semi-transparently one line at a time, which leads to the overlap problems.

]]> By: George Coulouris http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/comment-page-1/#comment-28297 George Coulouris Sun, 23 Dec 2007 21:57:54 +0000 http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/#comment-28297 Steve, Thanks for the comment about the key/menu on our (Camden CC) map. It took quite a lot of trial-and-error to get the DOM programming right for that one. So Andy, what is the secret to tone overlays? (Though I doubt it will be implementable with the Google API's polylines). One day we'll move to an open API (OpenLayers?) but not soon. Steve,
Thanks for the comment about the key/menu on our (Camden CC) map. It took quite a lot of trial-and-error to get the DOM programming right for that one.

So Andy, what is the secret to tone overlays? (Though I doubt it will be implementable with the Google API’s polylines). One day we’ll move to an open API (OpenLayers?) but not soon.

]]> By: Steve Chilton http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/comment-page-1/#comment-27955 Steve Chilton Wed, 12 Dec 2007 22:48:40 +0000 http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/#comment-27955 Yeh, sorry, I realised when I had posted it that it might not make sense because of context. I meant the Camden Cycle Campaign one that is transparent and is hyperlinked. Yeh, sorry, I realised when I had posted it that it might not make sense because of context. I meant the Camden Cycle Campaign one that is transparent and is hyperlinked.

]]> By: Andy http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/comment-page-1/#comment-27901 Andy Mon, 10 Dec 2007 18:00:33 +0000 http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/#comment-27901 Steve - which map are you referring to? There's four different ones linked to from the post! Steve – which map are you referring to? There’s four different ones linked to from the post!

]]> By: Steve Chilton http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/comment-page-1/#comment-27840 Steve Chilton Sat, 08 Dec 2007 19:31:32 +0000 http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/#comment-27840 I like the way the key works on this map. Transparency, rollover, etc. You might want to share your solution to tone overlays (at joins in cycle routes) with them! I like the way the key works on this map. Transparency, rollover, etc. You might want to share your solution to tone overlays (at joins in cycle routes) with them!

]]> By: Chris Smith http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/comment-page-1/#comment-27644 Chris Smith Sun, 02 Dec 2007 16:52:08 +0000 http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/#comment-27644 Sorry put the link in the wrong place - here it is http://www.ctc-maps.org.uk/ Sorry put the link in the wrong place – here it is http://www.ctc-maps.org.uk/

]]> By: Chris Smith http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/comment-page-1/#comment-27643 Chris Smith Sun, 02 Dec 2007 16:51:15 +0000 http://www.gravitystorm.co.uk/shine/archives/2007/12/01/reuse-and-prosper/#comment-27643 The CTC maps website would be a lot better using these maps rather than the Google ones. The CTC maps website would be a lot better using these maps rather than the Google ones.

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