Question

Convert OS Mastermap GMZ to 500m2 .dwg tile files

  • 1 November 2019
  • 5 replies
  • 6 views

Badge +7

I can see how I can covert OS Mastermap GMZ files (zipped GML) to .dwg. However is it possble to split the .dwg output into clean cut 500 metre squre tiles?

 


5 replies

Userlevel 1
Badge +10

Yes, you just need to create a 500m grid to clip them with

Userlevel 2
Badge +17

Hi @scarter,

You can use the Tiler transformer to split the data up into the tiles. This transformer will clip the features along the tile boundary, then assign row and column attributes to them.

To write the tiles out to separate DWG files, please enable Fanout Dataset on the writer, then use the _row and _column attributes in the fanout expression. For more info on Dataset fanouts, please see:

http://docs.safe.com/fme/2018.1/html/FME_Desktop_Documentation/FME_Workbench/Workbench/fanout_about.htm

Userlevel 1
Badge +10

Hi @scarter,

You can use the Tiler transformer to split the data up into the tiles. This transformer will clip the features along the tile boundary, then assign row and column attributes to them.

To write the tiles out to separate DWG files, please enable Fanout Dataset on the writer, then use the _row and _column attributes in the fanout expression. For more info on Dataset fanouts, please see:

http://docs.safe.com/fme/2018.1/html/FME_Desktop_Documentation/FME_Workbench/Workbench/fanout_about.htm

OS mastermap in geochunked 1km tiles includes features that fall across the boundary, it means you need to do some calculation to calculate the seed coordinate to use in the tiler

Badge +7

Yes, you just need to create a 500m grid to clip them with

Thanks for that, @ebygomm. This option seems more of a goer. I do have a 500m grid .tab file where the Tile field contains the 500m tile value (e.g.: TQ4092SW). It's that tile value that I'd want the output files to be called. So, any features from the GML that fall within TQ4092SW would output into a DWG file called TQ4092SW.dwg. And any features from the GML falling within TQ4157NE would output into a DWG file called TQ4157NE.dwg, and so on. Forgive me, I am an absolute beginner, how do I reference the tile grid as the clipping table?

Userlevel 1
Badge +10
If you read in the 500m grid as a tab file you can then send this to the clipper port of a clipper, whilst the gml features go to the clippee port. Tick merge attributes so the tile value from the clipper is transferred to the clipped data. You can then use this value as a fanout on your DWG tiles. You'll probably need to get rid of duplicates where features span more than one tile, you can do this with a duplicate filter, using the tile value and TOID as key attributes.

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