overview_image disable

[jordyke]

Hello,

is there an possibility to disable the generation off overview images in the database.
Can you tell us when these are generated?

[Menion]

Hello @jordyke
there are more situations that trigger the generation of these overviews.
What is the problem with them?

[jordyke]

Hello,
the problem for us is the size off the database at the end. We use a lot off tracks and sometimes we load +- 1000 tracks at once. This gives some problem with the size off the  tracks database. Idealy we would like to be able to disable the generation because off the cpu load when generating these tracks and the sql lite db sizes.

[Tapio]

That's a good point IMO. Never thought about them residing in my increasing db... Personally, I don't need the previews, it would be even better if there was a more condensed track overview.

[Menion]

Hi guys,
thanks for opening this topic > interesting and useful.

Changes in the next version
- I've detected that the app saved previews in PNG format, sorry for this. It will be changed to compressed JPEG so the average size will be around 40kb (instead of the current average size 250kb!).
- I've also added an option into Points/tracks settings to disable generating of previews upon import (Locus Map 4.12.1+).

[ta-ka]

Hi menion,
Could you also use jpeg format for Image map calibration? Currently Locus stores png image(s) in the created kmz file even if the original image is jpeg. The kmz size is about four times larger than the original jpeg size (quality 92%).

[michaelbechtold]

@Menion: what is the safe procedure to re-render the existing overviews - AND compact the database, pls?
Mine is 1.3 GB now ...

[Menion]

@ta-ka
so do you think, that JPG 80% will be ok in all cases? I believe it should be, but rather asking maybe more skilled people. As I see, after some tests with Joeloc, I also save map tiles with 80% JPG files, so it should be perfectly fine.

@michaelbechtold
I have a benchmarking tool that does this, but for now, it has a problem, it consumes more memory than it should. An inner problem I've not yet solved. So I'll rather keep it private for now:). Also, bigger previews were introduced this year. Older will still be a lot smaller, so it most probably won't help too much.

[jordyke]

@menion,

we still use classic, because the layout off the classic is better for our use on tablets. Will the change also be done on the classic version?

[Menion]

The core of the apps is identical, so the format used for storing data (using JPG instead of PNG) will be in both versions.

Extra settings that allow disabling generating previews for newly imported tracks will be anyway available for Locus Map 4 only.

[ta-ka]

@menion
I agree with you and Joeloc. JPG 80% should be fine.

FYI:
Google developers recommended jpeg quality is 85%.
Imagemagick's default jpeg quality is 92%

[Andrew Heard]

Hi guys,
thanks for opening this topic > interesting and useful.

Changes in the next version
instead of the current average size 250kb!

@menion - so every current track has 250kb of preview metadata? how to reduce or remove this space for existing tracks, or will be converted automatically? or must I long tap on every single image - 1000s of them. already asked by Michael.

but I don't see the new setting in latest LM4.12.1

[Menion]

You are too fast. New setting is in the end not available in the points/tracks settings, but added into "Expert settings" as "Track previews during import".

[Andrew Heard]

yes, a more appropriate place for it

[Menion]

@ta-ka
One user reported that a new change in "jpg" in Onboard calibrator broke his new maps. He uses semi-transparent PNG files as a source images. I was firstly thinking about extra optional settings, but maps from photos are so small, that I think it does not worth it. So sorry, in the next version, PNG will be used again. Thanks for understanding.