thanks for the test code.  I tried it out and sent some detailed feedback to hostmaster@jpct.net.  It's not essential to what I'm doing, but it sure helps...

thanks, i'll give it a shot.  it should be useful with non-applet apps in any event - e.g. downloading a World instance over a web service as an SOAP attachment or something.  I wish Sun had made all classes Serializable (and even Marshalable) by default...

I was under the perhaps naive impression that if all the objects' version ids were unchanged it would work.  And if there are awt classes in World that changed it would be a prob.  (Now that you mention it though i wonder if the applet's securitymanager might be disinclined to let me do it since it bypasses teh constructor.)  i like Serializable for *local* app caches still - saves load time and is a big programmer conveience to save state between vm instances.

Hmm, looks like it might or might not work across jdk versions...
http://java.sun.com/j2se/1.4.2/docs/guide/serialization/spec/version.html#wp4602  

i guess if an applet gets an exception when deserializing (old vm), i can revert to recomputing it.  so it would run fastest on the latest sun plugin since that vm is what i would use to serialize it, if it works at all.

Sweet.  And one last thing - if World and it's all it's potential children are java.io.Serializable, then I can pre-compute it and save it off to be able to quickly reload it later....

thanks for the helpful reply.  i am not going to stream.  they'll just have to wait while the applet downloads with the 40M of data inside the zip, then it will be fast after that while they are using it, or so i tell myself  And the software renderer is no prob.  The terrain demo runs at 7 fps on my old 200mhz laptop, which is fine for this purpose.  So i guess it will work with the MS VM and Sun plugin, blah blah?  do you know if not using BufferedImage in 1.1 hurts performance terribly?  and do you cull stuff in the line of sight but far away?  if so i will make the background mist colored and it will be fine otherwise i might have a prob since there is alot of terrain in any direction.

I am thinking about cobbling together an interactive applet viewer for some large dataset public domain elevation data from the USGS (for the curious it's in ".BIL" format - an integer raster).  Basically I am just grabbing sections out of the file and moving around in the canyons etc and viewing it from different angles, like a virtual hiker, maybe overlaying some satellite vegetation coverage data if i get carried away.  Do you think jPCT would be a good choice for that, and/or do you forsee any pitfalls?  Or has someone already solved this problem...