SVG Layers

Likewise, when SVG Exporter is doing its Adjusting, Merging and Morphing operations, each of the 12 layer is treated differently. Some layers are left untouched by the operations; some layers are morphed, some are merged and some adjusted. Part of the scheme for doing this was taken from David McKenzie's Walls program. To maintain compatibility with Walls-generated maps, the SVG Exporter uses some of the same names as Walls.

There are four basic types of layers:

A. Empty, Unadjusted Layers. Empty layers are placed in the file for your own use. They are not adjusted by the exporter so you can safely put any drawings, text, or images in them.

B. Replacement Layers. The exporter always replaces the data in replacement layers whenever it does the morph/merge process. These layers contains things like shot lines from data. Since the shot lines change when you correct errors, add new surveys or just move the cave to a different place on the paper, they are always replaced. For that reason, you should never put any of your own drawings in these layers.

C. Adjustment Layers. The exporter moves and scales objects in Adjustment layers, but does not rotate or warp them. The layers are intended for objects that need to move with the cave, but don't need to be rotated or warped to follow the changes in passage shape and angle. For example, you would normally want text labels to be oriented so the top is oriented toward the top of the map.

The two images to the right show how the text doesn't rotate while moving to track the changes in the passage angle. The passage angle has changed by about 40 degrees while the text is still oriented with the top of the text toward the top of the paper.

D. Morphing Layers. In addition to moving and scaling, items on the Morphing layers are reshaped or warped to follow changes in the relative position of passages. For example, if you repair a survey error and two passages come together at a different angle, the passage wall lines will need to be compressed so they maintain the same position relative to the wall.
The images to the right show a passage corner where an error correction has changed the angle by 20 degrees. You will notice how the program has stretched and opened the inside wall. I has also stretched the "slope symbol: right at the corner so it maintains its position relative to the shots, the stations and the passage walls.
Any text placed on a Morphing layer will not be warped, but the individual letters and will moved, scaled and rotated so they maintain the same position relative to the passages. In other words, if you have you a curving line of letters that follow a stream, the text will maintain the same curving in relation to the passages.
The two images to the right show how text placed on a morphing layer will be rotated and maintain its same relative position to the shot lines and by extension, to the passage walls.

It is important that you understand how each layer works and what parts of your cave map should placed on which layers. To help you understand the layering system, here is a detailed description of all the layers:

1. w2d_Frame - This layer contains a rectangular frame forms a border around the edge of the map. It defines the margin for the map. Anything outside the frame is consider part of the margin which means that it is beyond the printers ability to reach. Because the frame is based on the paper size, it is erased and new one inserted by the Exporter every time you do a Merge/Morph. This allows you to change the size of the paper with the exporter. As a result, you shouldn't put any other drawings in this layer because the Exporter may erase them.
2. w2d_Legend - This layer should contain any legend information you want to add to the map. The exporter doesn't adjust this layer.  You can add your own sub-layers to this layer to organize your legend information.
   • NorthArrow - This sub-layer contains a north-arrow generated by the exporter. The north arrow is replaced every time a merge/morph procedure is performed so you should not put any hand-drawn north-arrow in this layer. If you need a separate north-arrow, create your own sub-layer under with a different name. Put your sub-layer directly under w2d_Legend, not under the NorthArrow layer.
   • ScaleBar - This sub-layer contains a scale bar generated by the exporter. The scale bar is replaced every time a merge/morph procedure is performed so you should not put any hand-drawn scale bar in this layer. If you need a separate scale bar, create your own sub-layer with a different name. Put your sub-layer directly under w2d_Legend, not under the ScaleBar layer.
3. w2d_Grid - This layer contains a grid of lines marking distances on the map. The Grid  is erased and new one inserted by the Exporter every time you do a Merge/Morph. As a result, you shouldn't put any other drawings in this layer because the Exporter may erase them.
4. w2d_Notes - This is a Walls layer that is included for compatibility sake. It normally contains notes from survey data. At this point Compass doesn't use this layer. Future versions may make use of this layer. You should avoid using this layer since future versions may erase any data contained in the layer.
5. w2d_Labels - This layer contains Labels for survey stations. The Labels are erased and new ones inserted by the Exporter every time you do a Merge/Morph. As a result, you shouldn't put any other drawings in this layer because the Exporter may erase them.
6. w2d_Survey - This layer contains survey shot lines and markers from your cave.  information from you cave. The shot information is erased and new information is inserted by the Exporter every time you do a Merge/Morph. As a result, you shouldn't put any other drawings in this layer because it may be lost.
   • w2d_Markers - This layer contains markers for each survey station. Do not put your own drawing information in the layer as it may be lost.
   • w2d_Vectors- This layer contains shot lines for each shot in the cave. Do not put your own drawing information in the layer as it may be lost.
7. w2d_Walls - The two sub-layers under this layer will contain the main features of the cave such as your passage wall drawings, text associated with the passages, etc. The exporter adjusts these sub-layers so they match any changes that have occurred to the cave or any changes you made to the layout of the map in the Exporter.
   • w2d_Walls_sym - This layer should contain any drawings, symbols, text or other items that should be moved or scaled when the cave changes, but not warped, morphed or rotated. For example, text that should always be oriented toward the top of the map should be placed in this layer.
   • w2d_Walls_shp - This layer should contain any drawings, symbols, text or other items that should be moved, scaled, warped, morphed and rotated when the cave changes. For example, the passage wall drawings need to be moved if the cave moves, scaled if the cave passages get longer or shorter, rotated if the cave is rotated and warped if the passages move relative to each other when an error is corrected. You should place any text in this layer that curves to follow the passage.
8. w2d_Detail - The two sub-layers under this layer will contain small details of cave such as floor detail, ceiling details, symbols for breakdown, stalactites, stalagmites, sand, clay etc. The exporter adjusts these sub-layers so they match any changes that have occurred to the cave or any changes you made to the layout of the map in the Exporter.
   • w2d_Detail_sym - This layer should contain any drawings, symbols, text or other items that should be moved or scaled when the cave changes, but not warped, morphed or rotated. For example, ceiling height circles whose numbers should always be oriented toward the top of the map should be placed in this layer.
   • w2d_Detail_shp - This layer should contain any drawings, symbols, text or other items that should be moved, scaled, warped, morphed and rotated when the cave changes. For example, the slope lines and drop-off symbols need to be moved if the cave moves, scaled if the cave passages get longer or shorter, rotated if the cave is rotated and warped if the passages move relative to each other when an error is corrected. You should place any text in this layer that curves to follow the follow the shape of the passage. For example, text labeling a stream would fall into this category.
9. w2d_Mask - The mask layer is used to contain a colored back ground for the cave passages. Normally, a mask is created by making a copy of the passage outline and filling it with color. There are instructions for doing this in the Inkscape tutorial under the adding masks section. The exporter adjusts all items on all sub-layers by moving, scaling, warping, morphing and rotating the individual lines. In that sense it is handled identically to the w2d_Walls_sym layer.  You can have multiple mask for different situation and you can add your own sub-layers for each of those masks.
10. cmp_tracing - This layer is added by the Compass exporter and it is used for items involved in the tracing of passage outlines.
    • cmp_Sketchmap1 - This sub-layer is placed in the map by the exporter. It is designed to be a place to put sketch maps for tracing. The exporter does not make any changes to the content of the layer.
    • cmp_Sketchmap2 - This sub-layer has the same purpose and function as cmp_Sketchmap1.
    • cmp_LRUDs - This layer contains LRUD markers for each station in the cave. They are used to help trace the passage outline by providing an accurate indication of the wall positions. The exporter always erases the content and replaces it with new LRUD markers. You should not put any of your drawings in this layer.
    • cmp_passage - This layer contains computer-generated passage wall outlines for the cave. They are used to help trace the passage outline by providing an accurate indication of passage shapes and wall positions. The exporter always erases the content and replaces it with new passage models. You should not put any of your drawings in this layer.
11. w2d_Ref - This layer is generated by the exporter and it contains reference information about whether the cave is viewed in plan or profile view, the angle rotation around the vertical axis, the size of the map in cave units and the center of the plot. The exporter can read this information and reconstruct the exact positioning and size of the cave on paper. This allows you for the new map to duplicate the original may layout. Since this layer is always modified by the exporter, you should not put any of your own drawings in this layer.
12. w2d_Background - This layer contains a colored background for the cave map. The size of the background is based on the size the frame, which base on the size of the paper. As a result, the background color is generated by the exporter and is replaced every time you do a Merge/Morph operation. That allows you to change the paper size in the exporter. If you need custom background you should create your own background layer. But bear in mind that if you change the size of the paper, you will need to change the custom background size manually.