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Slicing a map into tiles

Maps can be sliced into tiles (e.g. squares of 256x256 pixels) on a desktop computer before being imported into Multiplans. Doing this slicing is useful for large maps, because importing a sliced map into Multiplans is much faster than importing a large map image.

There are many ways to slice a map into tiles.

The simplest method: Zoomify Express

The easiest way to slice a map into tiles is to use the program Zoomify Converter. This program is part of the free package Zommify Express, which works on both Mac and Windows platforms.

Zoomify Converter recognizes several graphic formats (jpg, png, tiff), but not format ecw. The png format is apparently only supported on the Mac version of Zoomify Converter. To import an ECW map, it must first be converted into a jpeg file (using GraphicConverter for example).

The tiles created by Zoomify converter are put in one (or several) folder(s) entitled "TileGroup0", "TileGroup1", ... To transfer these tiles into Multiplans, create a zip archive containing the folders "TileGroup0", "TileGroup1", ... .
On MacOS, select folder or folders "TileGroup0", "TileGroup1", .. Right-click on one of them and choose option "Compress …".
On Windows, use for example WinZip.

To calibrate the map, one adds of course a calibration file (ref.txt or a .map file) into the zip archive.

Note: In the current version, Multiplans uses in fact only the tiles corresponding to the maximum zoom level. Multiplans is though under active development and a future update is planned to recognize all zoom levels.

Though slicing with Zoomify Express works well, one might want to use another program to do the slicing for some reason (for instance to automate the slicing process for large map collections). In this case, use one of the methods explained in the next section.



More advanced methods

One can use also other programs to do the slicing, like GraphicConverter, ImageMagick, TileMage, Photoshop, etc.

The idea is to generate tiles that have a fixed size (square or rectangular) with sides measuring approximately 256 pixels. Do not make tiles larger than 300 pixels, as this might cause slow scrolling and memory issues. The tiles must be named along the scheme
where x and y represent, respectively, the column and line number of the tile. The format of the tiles can be jpg or png. The tiles can alternatively be named along the scheme used by program Zoomify Converter, that is names of the form "zoom-x-y.jpg". The numbering of the tiles need not begin with tile_1_1.jpg. It may also start with tile_0_0.jpg, or even any other value xmin_ymin. All the tiles must be compressed into a single zip file before being transferred into Multiplans.

Help for slicing using various programs:

Note for advanced users: You can make a map extending on a very large area (like a whole country), and add the corresponding tiles only when needed. Multiplans will simply display "tile missing" for any tile it can't find in the archive. To avoid errors when georeferencing such a map, it is recommended to always include the first tile "tile_1_1.jpg" in the archive, as that tile contains to the most northerly and westerly point that is referenced to in file ref.txt.