Increase "Own Vessel" render update time

[Moo]

Originally Posted by imp-cruiser

Sure. Temporary link: https://nextcloud.svbaelen.org:444/i...PSMfcLgk5zXmAz

More info on the replay method in file header (stream.py).

Looking at your data. The time stamp has decimal places to x.xx . This, AFAIK, is not part of the RMC sentence so will probably be ignored. Others will clarify. My usual NMEA playback app just rejects the whole file as non valid NMEA and that is all I see wrong at a quick glance.



If you want faster updates it may have to be provided in other sentences that support that.

[imp-cruiser]

Originally Posted by Moo

If you want faster updates it may have to be provided in other sentences that support that.

Thanks, Moo, I'll look into it :-).

[Moo]

Originally Posted by imp-cruiser

Thanks, Moo, I'll look into it :-).

Although I suspect that O is just ignoring the decimal time (or accepting it just fine) because playing your file here I see very smooth updates when there is information to update.



I played your file with the VDR plugin as my usual app (GpsGate) rejects it. I didn't try your stream.py but looking at the code it uses TCP perhaps there is an issue with that .. Perhaps try VDR? or change stream.py to use UDP?


Chris

[imp-cruiser]

Sorry to bump this old thread, but I had some time today to check this again.
I tried with several NMEA files and with the VDR plugin, but the ship icon keeps getting updated every 1 second (both in North Up and in Course Up).

The ship's longitude and latitude are getting updated much more frequent though (>10 x second), but the icon does not.

I also read something here;
"The Own Ship and AIS icons are still updated every second.", so this does seem to be normal behavior?

[CarCode]

How many miles runs your ship within one second?

[imp-cruiser]

Originally Posted by CarCode

How many miles runs your ship within one second?

About 7km/h; so 0.0012 miles/second?

[CarCode]

Originally Posted by imp-cruiser

About 7km/h; so 0.0012 miles/second?

So the ships icon update rate of one second seems enough or not?

[imp-cruiser]

Well, I was hoping to increase the update time, to e.g 0.25 seconds, or at least faster than one second.

[Moo]

Just checking: What version of OCPN are you using because, as myself and others have found, the updates happen as fast as they come in.


Lets have the full technical specs of you system and software version. Perhaps there is some other bottleneck in your system. Because nobody else sees this problem.



Chris

[bcn]

Originally Posted by imp-cruiser

About 7km/h; so 0.0012 miles/second?

4kn or aprox. 2m/s

2m is more or less the error you can expect from a standard GPS or the jitter you might see (there will be bigger spikes sometimes). With WAAS/EGNOS turned on we talk about an 1.2-1.5m error.

What (visualized) improvement in position you expect from a higher update rate then?
Some jitter of the rendered boat jumping 1px up and down and left and right you will get for sure.

[StuM]

More frequent graphic updates seem pointless to me.



At 0.1nm on the ruler (bottom left) on my laptop, two points 2 m apart both occupy the same pixel and the full screen is about 1 nm wide by 0.5 nm high.


Unless you use an even higher zoom, your vessel would not move more than once per second at 4 knots regardless of how frequently you sample.


At a more reasonable close in zoom of 1 nm ( 10 x 5 nm area of chart), you would have to be moving at 40 knots for the boat to move more than one pixel/second.



Considering the overhead of redrawing areas of a graphic display, doing so more frequently will make the program less responsive with no real benefit.



The status bar updates more frequently because it is a less CPU intensive operation and the display shows constantly changing values with minutes to 4 decimal places..


Which raises one of my pet peeves. Why show GPS positions to a false precision of less than 20 centimeters?

[imp-cruiser]

Originally Posted by Moo

Just checking: What version of OCPN are you using

Currently running OpenCPN version 5.0.0, built from source <https://github.com/OpenCPN/OpenCPN/releases/tag/v5.0.0>
(Note: I tried previous versions as well.)

Originally Posted by Moo

Lets have the full technical specs of you system and software version. Perhaps there is some other bottleneck in your system. Because nobody else sees this problem.

Yeah it's a bit strange :/.

Ubuntu 18.04.2 LTS
Machine: Dell XPS 13

[imp-cruiser]

Originally Posted by StuM

More frequent graphic updates seem pointless to me.

It is definitely not a "hard" requirement. As I said, it would be useful for simulation purposes, where I tend to speed up the data (e.g. x 10), which means a virtual vessel speed of approximately 20 to 30 m/s and more ...

Originally Posted by StuM

Considering the overhead of redrawing areas of a graphic display, doing so more frequently will make the program less responsive with no real benefit.

True, but I assume the impact will be relatively limited, no? Redrawing _only_ the vessel icon more than once per second is not that CPU intensive. I would merely use it in simulation mode anyway; for real sailing, one second is definitely enough (and optimizing onboard CPU load is much more critical there as well).

[bcn]

When the position changes the program has to evaluate the complete viewport and redraw it in case. Not just the vessel icon.
When rendering a displaced (vessel) icon you need to fill at least the "gap" left behind. And render the track..
Now add "heading-up", "auto-follow", chart boundaries, CPA lines....

[imp-cruiser]

Hm. That does imply quite some overhead. Thanks for clarifying.