kmz file size limitations?

[ecosys]

Hi,

 

I am converting shapefiles in ESRI ArcGIS10 to kml format and am having some trouble with them displaying on google earth, am wondering if there are file size limitations associated with them or have I got some other problem?  I am saving the shapefile as a lyr file first then converting to kml (kmz).

 

The sort of file sizes of my kmz files are 5 to 16 MB, which seems to be the upper limit as I had one that was 17MB and I just kept getting an error message when trying to open it in Google Earth.  And even with the smaller ones they are opening but are quite slow to display - Any suggestions or is it just a file size limitation?

 

Many Thanks in advance,

C

[Jason M]

Hi C,

The size of the KMZ is not major problem but the size of the
uncompressed KML file and the number of features -- that's the real
concern and what is loaded into memory.

For example, I've created KMZ files with 100K placemarks that had a 2-
minute startup delay but no other problems.
http://kml4earth.appspot.com/bigKml.html

When I tried tried 500K Placemarks (KML=68MB) this caused Google Earth
to have problems -- eventually loaded but only showed a small portion
of Placemarks and of those only one of the 25 types of icon styles.

If such a KMZ is composed of multiple KML files with Regions defined
in network links to load KML for a particular region when it is active
then you can manage very large KML/KMZ files. A single large
monolithic with many features tends to have performance issues. A
redesign/re-bundling of the KML in such a manner would allow it to
work reasonably well.

--jason

[ecosys]

Many thanks Jason, I'll give it a try!

 

Cheers

 

C

[Travis Cable]

I'm curious... did it work?

Thank you.

[ME]

I'd like to know, too.  My exported files from 0.1 to 11.5 mb all work well.  The lone large file, 64mb, pops up an 'out of memory' error.  This has complex geography and around 3000 features.

[Manish Deshmukh]

Hi Jason,

Would you please elaborate on how we can compose and use multiple KML files for a region to manage large data?

How would it know when and which KML file to load in the visualization ?

-Manish

[barryhunter (KML Guru)]

See

https://developers.google.com/kml/documentation/regions#regionbasednl

Its talking about using it for image overlays, but the same technique works just fine for vector data. 

There is even code that will take your 'big' KML file, and split it into lots of little ones

https://code.google.com/p/regionator/

(if you have Google Earth pro, its bundled) 

[Jason M]

The general rule of thumb is break it up large KML files into smaller KML files often all stored in the single KMZ file.

Then they are loaded via the parent KML file via NetworkLinks with Regions to only load those features that are in view. The parent KML should have each NetworkLink with the appropriate Region and Level of detail (Lod) element to prevent all of the KML files from loading all at once.

Google Earth can scale up to many millions of points and features but not all at once.

The exact number of what is "too large" takes trial and error. For example, 100K places may work in some situations, but crash Google Earth if each feature had a large size due to large amounts of inline HTML markup or ExtendedData, etc. Smaller groups of features such as on the order of 5K or 20K tends to work better.

As mentioned above, I posted described experiment by creating single KML files of 200K and 500K features. Things tend to break with that number of features.

--jason