32 lines
1.3 KiB
Markdown
32 lines
1.3 KiB
Markdown
= To Create a Timelapse =
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Set the field "begin" on each route in ```all_routes``` 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 ten meters (about 3500 total). On a EPSG:4326 projection, this means intervals of 0,0001. Turn on "Keep Attributes" as well.
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Each point in the resulting virtual layer 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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round("distance" * 100000, 0)
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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_time (String of length 20):
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```
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to_time(to_datetime( "begin" ) + (((3*60/1000*"distance")+0.01) || ' seconds'))
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```
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last_time (String of length 20):
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```
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to_time(to_datetime( "begin" ) + (((5*60)+(10*60*"distance")/1000) || ' seconds'))
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```
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Make certain all these values are saved, and set the layer to read-only (disable editing).
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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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