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All of the following instructions are based on the use of the Overlay Tool Bar. To hide or show the Overlay Tool Bar, select Overlay>Show/Hide Tool Bar from the menu bar at the top of the Map Module.
Lines
Creating New Lines
To set lines in Petra, select on the  button on the toolbox. Next, click where you want the beginning of the line to start. Clicking the left mouse button again will add further control points, while clicking the right button will end the line. The DELETE key will remove the last node point. After you finish adding control points on the line, the Overlay Line Attributes dialogue box will pop up.
Drawing an Arrow
To add an arrow, simply click on the arrow icon on the mapping toolbox. This will change your mouse to a crosshair. To add the arrow, first click on position for the head of the arrow, and then click again to place the tail.
Editing Existing Lines
To select and edit lines, depress the SHIFT KEY and then click on pre existing lines with the left mouse button. Another method of selecting lines is to first click on the red arrow on the toolbar, which brings up a crosshairs for your mouse on the map module, and then select the line you wish to edit with one click of the left mouse button. In either case, selecting a line changes the color of your line to blue and shows all the control point points in the line. Occasionally after making many changes to lines, it is necessary to redraw the screen to see the changes or to continue editing.
Moving individual control points - change the location of any blue boxed "control point" on the line by clicking and dragging it to a new position.
Moving whole lines - To move a whole line unchanged, press the ALT KEY and click on the line with the RIGHT MOUSE button.
Adjusting sections of line - To move entire sections of a line, press the CTRL KEY and choose two points on the line using the LEFT MOUSE button. Depressing the CTRL KEY and moving any section of the line in between the two selected points will stretch that entire section of the line.
Adding control points - select the "Add Ctrl. Point" button that looks like
 and add control points where necessary.
Dropping any control point - select the "Drop Ctrl. Point" button that looks like
 and click on existing control points for the selected line.
Increasing or decreasing the total number of control points to the line - choose "Smooth" or "Simplify" on the toolbar. "Smoothing" the line or polygon will place a new control point between every existing point, while "simplifying" the line or polygon will reduce the number of control points.
Copying a line - click on the copy button that looks like
 . To paste the line, click on the
 button and place the text.
Text
Creating Text
To set text, click on the "abc" icon button on the toolbar. Petra first asks you to establish a baseline that shows where you want the text and then builds a rectangle to establish the height of the text.
Editing Text
To edit pre existing text, first depress shift and then click on the text you wish to edit. Another method of editing text it to click on the red arrow button on the toolbar, which brings up a crosshair for your mouse on the map module, and then click on the text you wish to edit with one click of the left mouse button. Either method brings up a blue box around your text and allows you to edit the text. Sometimes after manipulating a piece of text multiple times, it may become necessary to refresh the screen to see the blue box that highlights text.
Editing Text Boxes - double click anywhere inside the blue box. This brings up the Overlay Text Attributes dialogue box that allows you precise control over features, including degree of angle and text height.
Changing the location of the text - press the ALT KEY and click the RIGHT MOUSE button somewhere inside the box and drag it to the new location.
Changing the angle of the text manually - press the ALT KEY and click the RIGHT MOUSE button on one of the original control points that established the baseline on the bottom of the blue box.
Copying a text box - click on the copy button. To paste the text, click on the button and place the text
Working with Multiple Lines/Text Boxes Simultaneously
Multiple line or text items can be selected and edited as a group. To select a group of items, click the LEFT MOUSE button on each item while holding down the SHIFT and CTRL keys. You can select multiple lines as a group or multiple text items as a group, but not lines and text together. Once a group of items is selected. The "attributes" dialog can be used to edit properties such as color, layer, font, etc. Group selection of lines is limited to similar type of lines. For example, if the first line selected is a fault, then all other selected lines must be a fault. The same can be said for contour lines.
Images
Importing an Image File
To add an image file, simply click on the "Add Image File" button on the toolbar that looks like
 . After clicking this, Petra will ask you to establish a rectangle on the map screen where the image file will be placed. Then, Petra will ask you for the location of the file and the layer you want it to go into. Various scaling options are available under the "Options" tab.
Working with GeoTIFF Files
To insert a Geo-referenced image, click on the "Options" tab and then on "GeoTIFF World File". A dialogue box will pop up asking you for the name and location of the file (*.tfw).
Before importing a Geo-referenced file, make sure your project is in the UTM map projection. (For more information on how to do this, see Map Projections)
Clipping an Overlay
To concentrate on a specific area or exclude map data that isn't relevant to your interests in a specific field, use the clipping tools to remove superfluous information. Clipping an area in the map module will cut lines and drop text anywhere within that area, but will leave images alone.
Remove all overlay data inside a user-defined rectangle - select the "Clip Inside" tool.
Removing all overlay data outside of a user defined rectangle - select the "Clip Outside" tool.
To remove all overlay data outside of a user defined polygon - select the "Clip Outside Polygon."
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