27 lines
1.1 KiB
Markdown
27 lines
1.1 KiB
Markdown
= To Create a Timelapse =
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Set begin on each route to the start time of each race.
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Use Locate Points on Line to create a layer that has one point every meter (about 35000 total). On a EPSG:4326 projection, this means intervals of 0,00001. Turn on "Keep Attributes" as well.
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Each point will have a "distance" field, which calculates the distance of that point along the route. This may well be in hundreds of kilometers; check out the maximum value of the field, and if necessary, convert the distance to meters with the field calculator:
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Update distance:
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```
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"distance" * 100000
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```
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(The longest `distance` element should be around 21000).
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Generate a second-based offset for the first and last runner past each meter, and translate it into a time:
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```
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5*60+((10*60)/1000)*"distance"
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```
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Then, calculate
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first_runner (string):
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to_time(to_datetime( "begin" ) + ((3*60/1000*"distance")+0.01) || ' seconds')
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last_runner (string):
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to_time(to_datetime( "begin" ) + (5*60+(10*60/1000*"distance")) || ' seconds')
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Then use this layer as your starting point for Time Manager. Remember to save and mark the layer as read-only before starting.
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