An atlas is a map of the cave, subdivied in pages. It is useful when you need to printout the cave map and the map is larger than the papersize of the printer. In this case you print the map a piece (one page) at a time and paste the pieces together to compose the whole map.

When you create an atlas you should organize the structure of maps according to the atlas pages and specify carefully the under- and over-laying passages [M. Sluka 2006.11.26]. You add to the "map" commands the "preview below" and "preview above" commands with the proper maps ("preview" works only with maps not scraps). For example

  map map1.m
    survey_1.1
    ...
    preview below map2.m
    preview below map3.m
  endmap

  map map2.m
    ...
    preview above map1.m
    preview below map3.m
  endmap

  map map3.m
    ...
    preview above map1.m
    preview above map2.m
  endmap

To make an atlas you specify the option "atlas" instead of "map" in the "export" command,

    export atlas ...

Each atlas page has the coordinates of the page and its number in parethesis. There are also the numbers of the pages to the north, the east, the south and the west, and at the higher and lower levels. The page numbers are omitted if there is the layout option "page-numbers off".

If the option "title-pages on" is specified, title pages are included for each atlas chapter There are chapters when the configuration file has several "select" commands. For examples the following lines of configuration file produce two atlas chapters, the first with title map7 and the second with title map1,

   select map7@test7 
   select map1@s1.test7

The layout option "origin X Y Z m" specifies where the grid origin is placed. For instance, having fixed the geographical coordinates of the cave entrance with the command "fix 1 1529802.9 5089076.7 2214.6" in a survey, if you set "origin 1529802.9 5089076.7 2214.6 m" the lower-left corner of the central square of the grid coincides with the entrance. The option "origin-label" specifies the indices for the grid central square. For example "origin-label K 2" assigns indices (K,2) to the central square, using letters for the rows and numbers for the columns, as in the figure below (made using the option "origin-label K 2").

The pages of the atlas contain also a 5x5 navigation grid with the cave map in small scale. The central square of this grid corresponds to the map on the page. The size of this navigation grid can be defined with the layout option "nav-size". For example "nav-size 1 2" states to put three cells horizontally and five vertically.

The border of the page are zones of overlap with the neighoring pages. They are also links that allow to navigate in the atlas to the nearby pages (by clicking on the relative border). The width of these borders can be defined with the layout option "overlap". The default is 1 cm.

The layout option "legend on" adds a final page with the legend for the map.

Other atlas options concern the dimensions of the pages:

• "page-setup W1 H1 W2 H2 LM TM units", where W1 and H1 are width and height of the paper, W2 and H2 are those of the page, and LM is the left margin, TM the upper margin. For example, the default is "page-setup 21 29.7 20 28.7 0.5 0.5 cm".
• "exclude-pages page_list", states which pages must be omitted in the output. For example "exclude-pages on 2,4-7,9" leaves out pages 2, 4, 5, 6, 7, and 9. To find the correct page numbers, you can first make an atlas with the options "own-pages 0" and "title-pages off", and check on it the page numbers you want to omit. When you create the final atlas (without those two options) you specify the same page numbers in the "exclude-pages" option. (The page numbers in the final PDF might be different, but you refer to the numbers you got earlier in "exclude-pages").
• "nav-factor" sets the scale factor of the navigation grid. For instance the default is "nav-factor 30".
• "size W H units" sets the size of a cell of the atlas. The default is "size 18 22.2 cm" (good for A4 paper).
• "own-pages N" sets the number of the first page. For example if you specify "own-pages 100" the first page has number 101.

For example to generate A3 atlas with landscape orientation you can use the following options (the value 0.001 is used here because therion complaints about a value of 0):

    -layout-page-setup 42 29.7 40 28.7 1.0 0.001 cm 
    -layout-size 38 20.2 cm 
    -layout-overlap 2.0 cm 

If the layout size is too large you may get empty blank pages. It should be possible to specify just the size:

    -layout-size 38 20.2 cm