[AMCL] reduce the amount of memory used

[facontidavide]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	none
Primary OS tested on	Ubuntu
Robotic platform tested on	Simulation
Does this PR contain AI generated software?	No

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Description of contribution in a few bullet points

This is a memory optimization that should not affect realtime perfomance, but will reduce considerably the amount of memory used by AMCL.

In our large map (200 Mb) this is the memory usage before the change:

And after the changes:

The main changes are:

1. Changes in map_cell_t: reduction from 12 bytes to 5 bytes
2. Add a new parameter to reduce the memory used by free_space_indices using 1/4th of the points (equally spaced)

Description of documentation updates required from your changes

Describe the new parameter "freespace_downsampling"

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Future work that may be required in bullet points

To be discussed

For Maintainers:

• [ ] Check that any new parameters added are updated in docs.nav2.org
• [ ] Check that any significant change is added to the migration guide
• [ ] Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• [ ] Check that any new functions have Doxygen added
• [ ] Check that any new features have test coverage
• [ ] Check that any new plugins is added to the plugins page
• [ ] If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[doisyg]

~~Noting that it corresponds to a new (smaller) maximum side size of 3.2 km for AMCL maps at a standard resolution of 0.05m/px. I think that it is fair and that we don't have any use cases of nav2 with maps that big. I expect other part of the system to fail before a map side . wdyt @SteveMacenski and @tonynajjar ?~~

[mergify[bot]]

@facontidavide, your PR has failed to build. Please check CI outputs and resolve issues. You may need to rebase or pull in main due to API changes (or your contribution genuinely fails).

[facontidavide]

UPDATE: sorry I don't understand why this PR include files outside nav2_amcl. I will clean it up

Also, I removed the limitation in terms of maximu size of the map, so ignore the 3.2 km remark from @doisyg

[mergify[bot]]

@facontidavide, your PR has failed to build. Please check CI outputs and resolve issues. You may need to rebase or pull in main due to API changes (or your contribution genuinely fails).

[mergify[bot]]

@facontidavide, your PR has failed to build. Please check CI outputs and resolve issues. You may need to rebase or pull in main due to API changes (or your contribution genuinely fails).

[mergify[bot]]

@facontidavide, your PR has failed to build. Please check CI outputs and resolve issues. You may need to rebase or pull in main due to API changes (or your contribution genuinely fails).

[SteveMacenski]

freespace_downsampling_ needs to be a class member, that should get CI unblocked

[SteveMacenski]

Still a draft, should I merge this in?

[facontidavide]

if it is good for you, it is good for me. I will prepare tomorrow a PR for the documentation https://docs.nav2.org/configuration/packages/configuring-amcl.html?highlight=amcl

[facontidavide]

Party on! What's next for memory consumption? 😎

:smile: sparse costmaps ??? Not yet... not yet...

[SteveMacenski]

Please do update the configuration guide docs for this param. You can also announce it in the Iron->Jazzy migration guide file since Nav2 hasn't forked for Jazzy yet (still working on it..)

😄 sparse costmaps ??? Not yet... not yet...

Well before you go nutty there, lets discuss that. I have a broader plan for costmaps in the medium term future :wink:

[facontidavide]

Well before you go nutty there, lets discuss that. I have a broader plan for costmaps in the medium term future

Keep me in the loop! I am sure I can take some work out of your plate :wink: