Document how plugins should transform data #915
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Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>
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Since this is only changing a markdown file, I think the PR job is enough CI. |
Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>
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| Data without an associated time should be transformed using one of the functions that does not accept a time. | ||
| This will use the latest available transform data. |
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I'm wondering if this is the right thing to do. It may be that's what we're doing historically, but we do also have the sent and (sometimes) the received timestamps in the message info. One or both of these is likely to be more accurate.
There is an assumption with the current text that the time between the data being sent, being received, and being rendered are all very small. Which hopefully is the case, but maybe not.
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So maybe just a mention that you should try to use the time sources in this order:
- from a Header
- the sent timestamp
- the received timestamp
- no time (latest transform)
I'm not sure there's really any situation where you have no timestamp, but it could be possible if the data comes from something other than a ROS topic (maybe a service call or maybe the user clicking on the screen or something).
Resolves #894
This documents how display plugins should handle time and transforms.