On Sat, May 7, 2011 at 3:58 AM, Scott Crosby <[email protected]> wrote: > Yes, but via a different mechanism. Create a new blob type: > 'OSMInvisibleHistoryData', it will contain a serialized ordinary > PrimitiveBlock > message. In this block you'll place invisible nodes/ways/relations. Standard > readers will see this block and skip right past it. Your reader will feed it > to the > normal pbf decoder function and have it mark those entities as invisible. > You'll > want to indicate these files with a new optional_feature > 'ContainsInvisibleHistoryData'.
I like the idea. You can heave InvisibleNodes / InvisibleWays / InvisibleRelations / InvsibleDenseNodes blobs. Their encoding / .proto would be exactly the same as for the normal blobs. Readers not interested in the data can skip invisible objects, existing readers would always skip them ( they do not recognize the blobs ). > What else do people want to consider putting in? Anything else that would > help in recording history? Consider adding LZMA? Someone want to run a test? A small wish list ;-) - dense ways / relations - optional feature: ordered ( nodes -> ways -> relations ); actually some readers already assume this - if ordered: position of first node / way / relation block - optional feature: polygon / bbox used to filter the data set - name / id / url / ... of the data set? - include .proto definitions in the file format? -> self describing; might be of interest of we ever break compatibility; or if you want to read PBF files that were extended by a writer and don't want to hunt down the definitions With regard to LZMA: I have some C++ code lying around to compress / decompress LZMA... I can test how much it would affect file size / decoding speed. Regards, Christian Vetter _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
