The drawing of a cave map is made, besides of symbols (points) and labels, of lines, curves that denote the walls of the cave, and other linear features. To draw a line select the menu "Edit | Insert - line" (or Ctrl-L). The message in the status bar changes to "Insert line point": infact a curve is defined by a few points in key positions (sharp corners, middle of a regular piece, etc.). When you are in insert-line mode every point where you click becomes a new point of the line. To end the line you can click on the "Esc" key (and go back to select mode), or you can press Ctrl-L and start inserting points of a new line.

You can draw two kinds of lines: polygonal lines (made of straight segments between the points that you click) and smooth curves. For the former you need to click in the vertices of the polygonal line. For the latter you must click in a point and drag the mouse. This produces a straight segment with the point in the middle and two little squares at the ends. These squares are the control points of the line point. The yellow square is in the forward direction, the red square is backward. The directin of this segment and its length define how the line must pass through the point, ie, its direction and curvature (it depends also on the half-segments of the previous and the next points on the line). If you need that a segment determines the line only forward or only backward you must deactivate the relative checkbox in the "Line points" control: "<<" to deactivate the backward, ">>" for the forward. The checkbox "smooth" is active when both the other two are active. This way you have a complete control over the curve.

Lines in therion have a starting point (the "begin") and an end-point (the "end"). The starting point is marked by a small transversal yellow tick in xtherion. Lines have an orientation, ie, a left side and a right side: the left side is the side that contains the yellow tick. When you reverse the line (option -reverse on, the yellow tick flips on the other side, and it is at the "end" of the line.

Lines, like the points, have a type. A few types are:

• wall, for the walls of the cave;
• contour, border;
• chimney, floor-step, pit, overhang, slope;
• rock-border and rock-edge: the first for the border of blocks, the second for the internal edge lines; flowstone, moonmilk
• section for the segment of a cross-section;
• arrow, gradient, are lines ending with a arrow
• water-flow.
• label, map-connection.

For some line types the orientation is important as it affects the way the line is drawn. For examples the ticks on a pit line are drawns on the "left side", therefore you must draw the pit lines with the left side where there is the drop. The figure below shows the line types with orientation: all the lines have been traced with the tick pointing in the direction of the arrow. The "slope" line is drawn with only the transveral segment: a "border" line has been traced just underneath it to show the position of the line.

Therion distinguishes among floor-step, a short drop or slope that does not require equipment, pit and overhang, which require ropes and equipment.

Lines of type contour can have a -gradient option. This can be -gradient none (nothing is drawn), or -gradient center (the tick is drawn in the middle point, default). It is also possible to add the option gradient point after all the points where you want to draw the tick (you must write "gradient point" in the option box of the line point in the map editor, or you can edit the map file with the text editor).

Lines of type slope are drawn as segments oriented perpendicularly to the line, starting at the line points. Therefore the orientation of these segments depends also on the control points. At least one of the points of a slope line must have a l-size option which defines the length of the segments. Each point can have an orientation which modifies the default orientation of its segment. When you highlight (ie, select) a point with the l-size value, this is displayed with a red arrow. You can go over the arrow with the mouse (the arrow becomes yellow) and stretch or shorten it, thus modifying the l-size value.

Slope lines have also the option -border, which can be on or off. By default it is "off" and the line from which the slope ticks start is not shown. To draw it set the option -border on.

Arrow lines have the option -head which indicates where to put the arow head. It can be "begin" (where the line starts), "end", "both", or "none". The default is "end". If you reverse the line, the begin and end points are swapped.

Label lines have a -text option to specify the text to write along the line. The text is written from the "begin" to the "end", and is oriented so that te left side of the line is up (and the right side is down). If you reverse the line the text is reversed.

Some types of lines (wall, border, survey and water-flow), just like the omonimous points, can have a subtype (option -subtype). For instance line of type border can be invisible. Lines (and points) can have the attribute visibilty set to off. The semantics between the subtype invisible and the attribute visibility is rather different. visibility off means that the symbol is there, but you want it not to be shown. For example the borders of areas that must not be drawn in the map. invisible is used to denote something that you do not see: for example to mark a scrap outline where there is no wall (a curved entrance), or when therion has problems to properly close the outline.

Another subtype is presumed. For wall lines it means that are presumed, so they are drwan with dashed lines. It can be used also for lines of type border.

If you write the option "-subtype xxxx" (with the dash) in the option field of the "Line control", the subtype applies to the whole line. If you write "subtype xxxx" (without the dash) into the black option window of the "Line point control" the specified subtype applies from that point to the end of the line. The "Line point" subtype overrides that of the "Line", and that of previous line points.

Therefore, you can draw a long (wall) line and change its subtype at its points. It is not necessary to divide the line into small parts according to their subtypes. The figure below shows a wall line with a global "presumed" subtype and two intermediate points with subtypes "blocks" and "bedrock".

Lines of type wall can have subtype bedrock, blocks, clay, debris, ice, sand, pebbles, unsurveyed, underlying, presumed and invisible. These are shown in the figure below (except invisible which says not to draw the line).

If you need to specify the altitude of a point on the wall, you can add an "altitude" option to the point (in the text box of the Line points section of xtherion). The syntax is "altitude value". For example "altitude +4", "altitude [-2 m]". It creates an altitude label attached to the wall point. The altitudes are exported as difference from the Z-value of the grid origin (which is 0 by default, ie, unless you fix the coordinates of some point). The value is the difference from the Z-value of the nearest station. However if the value is prefixed by the "fix" keyword, the value is considered as absolute altitude. For example "altitude [fix 1536 m]". If you specify a Z coordinate for the grid origin (eg, layout command -grid-origin 0 0 20 m) the value of the grid origin Z coordinate is subtracted from the altitudes (even from the fixed values).

If you would like to leave to therion to compute the altitude, just write "altitude .". The altitude points are marked on the map with a little tick and the numerical value.

The value of altitude points is specified by the "-value" option. For example "altitude -value [fix 1479 m]". The syntax for the value is like that of the wall line points. The syntax "altitude ." can be used for the altitude points, as well. The points are printed on the map as a dot with the numerical value. By default the number is centered at the dot. You can move it on the side, or at a corner by using the option "-align", for example "-align tl" ("tl" stands for top-left) moves the value to the top-left of the dot.

Lines of type water-flow can have subtype permanent, intermittent and conjectural. Lines of type border can have subtype invisible, temporary, visible and presumed.

The lines are oriented: they have a little yellow tick at the starting end. This should point toward the inside of the cave (where there is no rock). Therefore you should draw the walls of the cave counterclockwise, the blocks clockwise, pits and chimneys counterclockwise. If you make a mistake, you can invert the direction of the line by clicking on the "Reverse" button of the "Lines" control in the panel.

If a point belongs to two (or more) lines, when you select the point (left mouse button) a line is also selected. If it is not the line you wanted to select, you can alternate among the lines that pass through the point by clicking with the right mouse button on the selected point [thwiki 17].

Now insert the lines of the cave walls (type "wall"). If you make a mistake delete the line (Ctrl-D) and try again (Ctrl-L).

There are two ways to draw a closed line: either you finish by clicking on the starting point, or you use the "close" check-box of the "Line" control. If, by chance, you close a line that you didn't want to select the last point in the list in the "Line control" control. It should have the same coordinates as the first point. With the menu "Edit line" select "Delete point", and you remove it from the line (the first point remains on the line).

You can select each individual points on the line. Once selected, a point can be moved (drag with the mouse). You must click twice on the point: the first click select the point and it is displayed with a red circle around. When you click on the selected point a second time (and keep the mouse button pressed) you catch it and you can drag it around. Release the mouse button when the point has moved in the position you wanted.

To remove a point from a line go to the "Lines" control and select the button "Edit line | Delete point". To insert a point in the line, select, in the same control, "Edit line | Insert point". This button changes xtherion into line-point insert mode (for the selected line, that is the line for which the control was active), and you can now insert points. Every point is inserted just before the line point that is currently selected when you click "Insert point". Therefore, the first point is inserted between this point and previous line point; each next point is inserted between this point and the last inserted point.

To break a line at the selected point, select "Edit line | Split line" in the "Lines" control. If you want to break the line in a place beyween points, you must first insert a new point. More details in sect. 3.2 .

Symbols and labels are associated to points, ie, to their position in the drawing. Some symbols have an orientation. For example "water-flow" has a direction of flow: make active the "orientation" check box and select the orientation by rotating the yellow arrow attached to the point with the mouse, or by writing the value of the angle (in degrees) in the text box near the check box.

Unfortunately the symbols are not displayed in the map editor window, but only the points are shown, and it is rather difficult to remember what each point refers to. A little help comes from the status bar that displays the type of the point when the mouse is over it.

Labels are points of type label. The text to display must be written in the "options" textbox as -text .... Enclose the text in double quotes if it contains blank spaces. You may use HTML tags to format the text: <it>for italics, <bf>for boldface, and so on. Use <br>for a new-line, and <right>to right justify the text. The switch <lang:XX>specifes the language. The position of the text can be aligned to the placed point with the "-align" option. This takes values "r" (right), "l" (left), "t" (top), "b" (bottom), "c" (center), "tl", "tr", etc. For example "-align tl" means that the text is placed to the top and left of the point, ie, the point is the bottom-right corner of the text rectangle.

The text area is used to write a text that will be included in the drawing data file. It is used to add commands for MetaPost or pdfTeX (when one needs something special).

Select the menu "Edit | Insert - text", or in the "Objects" control of the panel, select the command "Action | Insert text". This opens the "Text" control, and you can enter your text in the black text-area. Whatever you write will be inserted literally in the data file.

As for the labels you can use HTML tags to format the text. For example to go to a new-line write <br>[thbook ...].

Now try it and insert a comment in your data file.

A cross section is a scrap and is associated to a position in the drawing of the plan or in that of the extended section. This position is specified with a point of type section and must have the option -scrap followed by the name of the scrap of the cross-section.

The scrap of the cross-section has another peculiarity. It usually has only one station; therefore it must have the option -scale so that therion can know its dimensions.

The cross-section is referred to in the (plan or elevation) map by a section line. This line has an option -direction to specify where to put the direction of view arrows. It can be "begin" (beginning of the section line), "end", "both", "none" and "point". The default is "none". The direction point option applies to the line points: it must be written after the line point, ie, in the text box of the xtherion "Line Point" control tab. Section lines are drawn differently than regular lines. When you place the line, make it a bezier curve and place the control handle that you use to bend the line around next to the spot where you want it to disappear. Do that on both ends of the line. The portions of the section line between the "inside" end points of any two consecutive control points are not drawn. You can also draw poligonal section lines.

Cross-sections are further discussed in sect. 3.6 .

Arrow lines
Contour lines
Slope lines
Altitude points