Offline maps on Android in China

[td_ref]

But when I try to download the map after clicking the "Create atlas" button I get the following error: Unable to find SQLite libraries. These are required for selected atlas format.

Motokai, if you haven't sorted "Unable to find SQLite libraries"
this is how i got it work:
download http://files.zentus.com/sqlitejdbc/sqlitejdbc-v056.jar, and place to same directory where Mobile_Atlas_Creator.jar is located.

SQLite (optional)
Some atlas formats uses a SQLite database for storing the tiles. For creating SQLite database the additional Java library SQLiteJDBC is required. MOBAC has been tested with sqlitejdbc-v056.jar - newer versions should also work.
Installation of the additional SQLite libraries is pretty simple: Just jownload the JAR file and place it in the same directory where Mobile_Atlas_Creator.jar is located. Alternatively you can place it in any path covered by the JAVA search path. The next time MOBAC is started the SQLite library is loaded and can be used."

[td_ref]

felix, thank you for sharing the infor corrects gps coordination. do you get that offset value by manual calibration?

[felix]

Hi td-ref, no problem i'm happy to share. I'm not sure what you mean by that question. I used googlemaps to calculate the offset, and it's actually quite easy:

(This only works in maps.google.com, it doesn't work with ditu.google.cn)

In googlemaps right-click on an intersection of two roads and select "what's here". That gives you the coordinates of that point, for example 31.375452, 120.951090
Then switch to satellite view, find where that intersection really is, and using right-click again get the coordinates for that, in this example it will be 31.377550, 120.946839
Then just subtract one from the other to find the offset. So in this example the offset is +2098, -4251

I get slightly different values every time i do it, but it doesn't make any big difference on the phone. Also remember that the offset is different in other parts of China, so if you're in Shenzhen you should find out what the offset is down there!

[chinabiker]

Hi td-ref, no problem i'm happy to share. I'm not sure what you mean by that question. I used googlemaps to calculate the offset, and it's actually quite easy:

(This only works in maps.google.com, it doesn't work with ditu.google.cn)

In googlemaps right-click on an intersection of two roads and select "what's here". That gives you the coordinates of that point, for example 31.375452, 120.951090
Then switch to satellite view, find where that intersection really is, and using right-click again get the coordinates for that, in this example it will be 31.377550, 120.946839
Then just subtract one from the other to find the offset. So in this example the offset is +2098, -4251

I get slightly different values every time i do it, but it doesn't make any big difference on the phone. Also remember that the offset is different in other parts of China, so if you're in Shenzhen you should find out what the offset is down there!

I did some investigation on the GM offset as well.

- The difference from now to next time may be related to the zoom factor.
- I heard the offsets are random (within certain limits) but Google folks seem to have a muzzle

I came across this website. hey have a database which might be useful - haven't checked it out though.

[ChinaV]

I did some investigation on the GM offset as well.

- The difference from now to next time may be related to the zoom factor.
- I heard the offsets are random (within certain limits) but Google folks seem to have a muzzle

I came across this website. hey have a database which might be useful - haven't checked it out though.

The algorithm has been cracked and and open sourced. It's not that difficult to program into an application, but it's a PITA if you're just trying to fix a single track. I'm sure someone will come along soon with a web based form where you can upload a kml file and convert it from correct to China or China to correct. I started working on it, but got scared. The reason you don't hear more about it is to avoid a re-setting of the algorithm by the gvmt.

Cheers!
ChinaV

[slabo]

Motokai, this is exactly the same problem you had before. To output sqlite files, you need to have that sqlite_jni.dll file in the mobac folder. Since you upgraded to mobac 1.8 that file is no longer in there.
Just do the same thing you did last time.

Euphonius, it's been hard work getting this far but it's nice that it's all sorted and working now. Are you sure you can't figure it out with the info in this thread? Extremely basic breakdown:
1 - Mobac 1.8 for your computer
2 - Oruxmaps for your android phone
3 - Edit coordinates in the xml file.

To all: never forget the power of google! I knew nothing about any of this a few weeks ago. FAQ and instructions already exist for Mobac and Oruxmaps, the only hard part is the china offset which i explained above.

If still needed, i may start a new thread with step by step.

#3 how exactly do you edit the coordinates in the xml file? I figured out how to calculate the offset, +/-xxx, +/-yyy .. but then you have to calculate the new coordinates for every point? It's an XML file, you used some xml editor or what? I never got to working with xml files so I don't really know my way..

Yes, this is from a year ago, but so far I've been creating maps and ignoring the China offset, or using my imagination on the road when in doubt, which got me into serious trouble once.

[felix]

Hi Slabo,

I use a program called notepad++ for editing, it's free and simple. I just open the .otkr2.xml file in that, change the numbers and then save. (back up the original file first in case you mess up)

Yes once you've worked out the offset you have to change every point in the file, but actually it doesn't take that long, there are 8 points for each zoom level. 10mins with a calculator is well worth it for having correct maps on your phone. You can round the last 2 numbers to 0 as they make very little difference, for example these are the corrections i use for the shanghai area:

lon -0.004600
lat +0.001900

One year later, i am still using this method. The latest version of oruxmaps is very good.

[Zuru]

Hi!

I'm glad I stumbled upon this post randomly. I am going to visit China in 10 days. As usual for foreign countries, I grab a map of the country with MOBAC, save it in .sqlite format for use in Locus application on Android.

I've noticed the strange mismatch between Google satellite photos and street maps, but hoped till the last that the street maps should be correct.

Anyhow, you were talking about "offset of death".
Are maps grabbed with MOBAC with this offset?
Does offset apply to satellite photos or to street maps?

Thank you! :)

P.S. In case you were wondering: Locus application - http://forum.asamm.cz/viewtopic.php?f=26&t=348

[ChinaV]

Hi!

I'm glad I stumbled upon this post randomly. I am going to visit China in 10 days. As usual for foreign countries, I grab a map of the country with MOBAC, save it in .sqlite format for use in Locus application on Android.

I've noticed the strange mismatch between Google satellite photos and street maps, but hoped till the last that the street maps should be correct.

Anyhow, you were talking about "offset of death".
Are maps grabbed with MOBAC with this offset?
Does offset apply to satellite photos or to street maps?

Thank you! :)

P.S. In case you were wondering: Locus application - http://forum.asamm.cz/viewtopic.php?f=26&t=348

Yes, your maps grabbed with MOBAC are going to be offset. Satellite view will probably be fine.

Cheers!
ChinaV

[td_ref]

I accidentaly found out that Gaode/autonavi GPS navigation app has native English support, I couldn't believe it it has been there for sometime in their android app. am I the first one who knows that, switching the system language also apply the application?
check this out FYI
http://c.autonavi.com/club/android/

the apk URL
http://mlbsdown.autonavi.com/navi/Autonavi.apk 30 day trial license before payment.
maps can be download by provineces over WIFI.