This is bit long-winded. But the experiments were interesting to run.

Using osmconvert, osmfilter, and osmandcreate I create a southeast USA .obf 
file.
Was going to process northamerica.pbf using an area selection that would 
only keep
the southeast USA. But my laptop does not have sufficient memory. So I 
process the 
USA a state at a time to keep only ...
--keep="highway=motorway =motorway_link =trunk =trunk_link =primary 
=primary_link"

Then merged the resulting .osm of each state with osmconvert64. 
Then converted the resulting .osm to .pbf with osmconvert64
Then created the .obf with osmandcreate.

The resulting .obf is 41 Meg-bytes. The original 15 states .obf
was 1.81 GBytes. So clearly a lot of data was deleted.

The processing took about 10 hours of CPU time on my laptop.
A 2.7Ghz dual core 64 bit cpu with 8GB ram with about 6.4GB ram
available to the user. Each state(florida_latest_2.obf ...)
was processed without using much of the
memory. The last step "osmandcreate" was run with
"java.exe -Xms4g -Xmx6g -jar osmandmapcreator.jar"
Memory usage peaked with abut 4.7GB used and
1.1GB available. This last step ran in a bout 45 minutes.

During the processing my laptop crashed twice. Not a software problem,
but a CPU over temperature shut down. Every laptop I have ever owned
does this to me when ever I keep the CPU's busy running for extended 
periods. I have two solutions I use when this happens. The easy solution is
to use the "advanced power options" menu to set the max processor state
to 10% instead of the default 100%. For most CPU's this means the cpu clock 
be limited to half of the maximum clock frequency. 
For my laptop this means running at 1.4Ghz instead
of 2.7Hgz. But I still got an over heat shut down. Had to use my old 
solution of cutting
an access hole on the bottom of the plastic case near where the CPU heat 
sinks are.
Add a spacer to raise the laptop and sit a fan next to my laptop. This 
solution turned
out to work very well and I went back to running the CPU at 2.7Ghz.

The resulting southeast_usa.obf was put on a samsung S6
and I'm using osmand 2.8.2. Yes. I know this is a little out of date.
I have all the various versions of OsmAnd up to version 3.2.6.
I experiment with all the versions but for some reason I call the
2.8.2 my baseline version. Does everything I need.

Choosing random "start" and "finish" points from the southeast USA
I ran many tests The table below are some of the results. At no time did
the software get "hung" computing a route forever. All computation times
scaled with route distance as would be expected

Below are typical routing times I am getting now.

Miles    Time to compute route(seconds)
-------     ----------------------------------------------
 241         4
 642       10
 742       12
 910       19
1506       49
1553       55

For distances of less than 100 miles the time to compute the
route was < 1 second and was basically instantaneous.

In all cases OsmAnd found what appeared to be the optimal route.
The route was typically withing a few miles of my intended destination.
Limited only by the road density of the filtered maps I provided.
(I did not move a favorite waypoint just because a road was filtered out.
I just let OsamAnd do its magic and find the closest road.)

If I took the time I could create a USA.pbf with the osmfilter
as shown above. The resulting .pbf would be around 250Meg
and the resulting .obf would be around 500Meg?? But my laptop
can not perform the last step due to insufficient memory.
If there was a usa.obf created as shown above, route times would
probably be in the area of 60 to 120 seconds to go accross the entire USA.
But I really don't see a need to route plan across the entire USA. 

I don't have high end phones. 
The Samsung S6 I used in the tests was given to me by a friend. My
personal phone is a Samsung Express 3.  
With 8GB rom (3.8G available to the user)
1GB ram ( 282Meg available to the user).
If I remain at the state level (instead of country), my laptop can 
easily create the data I need. And my phone will be able swallow the
data I give it.


Kevin





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