[2!v Talos Digitizer Interface Program User Documentation Ted Frohling 602-792-2800 Mountain States Engineers P O Box 17960 Tucson, AZ 85731 April 24, 1984 Talos Digitizer Interface Program Page 1 Running the Talos Digitizer Interface program is quit easy. The interface program works with the Talos digitizer tablet and an associated video terminal. The digitizing tablet has two areas designated by dark zip-tape lines on its surface. The lower area is designated as a menu area. You should use the right (smaller) menu of actions. The larger area above the menu area is the digitizing area. All points not within this area will be ignored by the interface program. The interface program works in conjunction with a video terminal of the VT100 variety. Before using the program, you will need to allocate the terminal line the digitizer is connected to. This MUST be done before the digitizer controller is turned on. The terminal line is currently associated with the logical name 'TALOS_DEVICE'. The allocation is made with the following DCL command: $allocate talos_device This allocation is necessary so, the VAX does not think the digitizer is trying to log in on its terminal port. After the port has been allocated, turn on the digitizer controller with the 'on/off' switch and ensure that the 'rate' dial is fully clockwise. The Talos digitizer tablet should be in the 'point' mode during program startup. This is accomplished by pressing the 'mode selection' button on the lower left corner of the digitizing tablet. On each press of the mode select button, the lower lights will show a new mode. The light next to 'point' should be lit. You should now run the digitizer interface program. This is accomplished with either of the next commands. $run msme$system:digitizer or $msr digitizer When the program starts up, the screen will be painted with several areas of text and reverse video blocks. You will be asked two questions to actually start the process of digitizing. The first question should be answered with the file name which will contain the digitized points. If you enter an carriage return without a file name the program will exit. For this reason you must record the digitized points to a file, even if you do not need to retain the points for later reference. In this case, simply delete the file just created, after leaving the digitizer interface program. Version numbers are not required or particularily necessary. The VAX will create a file with a higher version if you designate just the file name and extension and the file already exists in your directory. Any legal file specification may be used for the file. Next, you will be asked to enter a line of text to be associated with each digitized point. If you enter a carriage return with no characters you will be prompted for a new file name. For this reason, you must enter at least one character at this prompt. All tabs and spaces are translated to single spaces and the leading space, if any is deleted. If you enter a space followed by a carriage return the program will think you entered just a carriage return and send you back to the file prompt. After these questions the real work of the program starts. Talos Digitizer Interface Program Page 2 When the digitizer main program starts up, further input from the keyboard is generally ignored. It is assumed that further input will come from the puck. However, it is sometimes necessary to interrupt the input of digitized points to enter information from the keyboard. The Talos Digitizer Interface program can accomodate this. The puck contains a keypad with the numbers 0 thru 9 and the characters '*' and '#'. It is these last two characters which are used to interrupt the digitizing process. The asterisk is used to get the attention of the screen and keyboard and the pound sign is used at the end of various inputs to tell the keyboard that the puck has input of some significant value. Upon input of the * character on the puck, the main program is interrupted for the display of a short menu. The menu looks like the following: Action required: Function change F Text change for points T Base coordinate setting B Scale setting S Axis rotate A Help H Input action desired? To select something from the menu simply type the first letter of the word of a line. For instance, to change the function of the digitizer, type in the letter 'F'. Upper or lower case is ok. You could also type in the word 'function' if you wanted to, but only the letter 'f' is required. The letter typed must be followed by a carriage return from the keyboard. If you get to the menu by mistake, simply press a single carriage return on the keyboard to return to digitizing. When you enter a valid entry from the menu you will be prompted for additional information. This information can come form the keyboard or the puck or both. Let's explain each entry in the menu list. The 'Function change' entry allows you to change the function or the calculating routine of the digitizer interface program. The functions are, Point, Area and Length. The point function should be selected when you want to digitize a series of individual points from a map. The area function is used to digitize the outline of an area in a continuous fashion and expect to calculate the area of the delineated by the digitized perimeter. The length function is chosen when you desire to calculate the length of a line or series of lines. If you select the area mode you must manually put the Talos digitizer in the 'incr' mode. Use the 'mode selection' button on the digitizer (SEL) to put the Talos tablet in the 'incr' mode. The Talos modes, 'remote', 'run' and 'track' should not be used and the use of these modes will surely cause incorrect results. Talos Digitizer Interface Program Page 3 The 'Text change for points' is used to send a different line of text to the file for each subsequent point that is digitized. Entering a single carriage return or a space followed by a carriage return will cause the text to be left blank for subsequent points. The 'Base coordinate setting' is used to enter the map base coordinates and tablet physical point. You will be asked to enter the x and y map coordinates from the keyboard. Generally these coordinates should be a number less than 10000. You may need to do some number truncation of the map coordinates to stay within this range. For instance, if the base map coordinate for the x axis is 122000, then a reasonable entry for this axis would be 2000. Mentally, you will keep track of the 120000 that you left off. When you have entered the map coordinates from the keyboard, you will be asked to place the puck on that point and press the '#'. This point must be within the digitizing area. The 'Scale setting' allows you to specify a scaling factor to apply to all calculations done by the program. The Talos digititizer will allow you to pick 1000 points per inch. The setting of the scale is usually not a problem when you are using the English measuring system (inches, feet, etc.). If the scale of a map in question is 1 inch equals 600 feet; the scale for the program is 60 since the program is measuring 1000 steps per inch. In this example, the finest resolution for any point would be + or - 6. Problems can arise when you need to translate this system to metric measure. An illustration should help here. You will need an ruler with inches to complete the example. Measure the distance between two lines of coordinate data on the map. To get the scaling factor divide the units that are represented on the map for that distance by the measured distance and then divide this result by 1000. For example, a metrically scaled map is shown to have a scale of 1:2500 meters. The map in question has stadia lines every 200 meters and the distance measurement between stadia lines is 3.125 inches. You divide 200 by 3.125 and then by 1000 to arrive at a scale of .064. After you enter the x scale, a carriage return for the y scale will duplicate the map's x scale. Each scale can be different, it that is necessary. The 'Axis rotate' is used to correct for misalignment between the map coordinates and the digitizing tablet. This correction factor is based on measuring the relative skew about the x-axis. It may be positive or negative. After selecting this option you will be asked to place the puck on two points on the map's x-axis; the left-most x,y pair and then the right-most; pressing the '#' at each point. (Remember to stay within the tablet digitizing borders). You must put in the left-most x,y pair first. When both points have been entered, an angle of rotation will be displayed. The angle will be used to translate all digitized points to true map coordinates. Talos Digitizer Interface Program Page 4 The 'Help' will allow you get some help about the program during its running. The menu area on the digitizing tablet is available at any time during the digitizing process. Currently there are three choices. They are, 'Reject', 'Beep on/off' and 'Finish input'. Simply place the puck crosshairs in the appropriately labeled box and press any of the numbers on the puck. While these menu items are available at any time, you will find that they work best when the digitizing tablet is in 'point' mode. The 'Reject' will allow you to remove from memory the last point(s) entered. For example, if you entered 10 ponts but wish to delete the last four, you would place the puck's crosshairs in the 'Reject' box and press any number on the puck four times. The 'Beep on/off' allows you to turn on the terminal bell for each point that is digitized. This is handy for point mode or length mode so you don't have to look at the screen to know that the point has been entered. You may turn the beep on and off with the same selection; like a light switch. Beep is off when you are in the using the area function. The 'Finish input' tells the program that you are finished with a set of points and want to move on to something else. This is the only way to leave the program and actually save your digitized points to a file. In other words, don't type a control-C or control-Y and expect to save any information. Digitizing is quite simple as long as a couple of things are remembered. To enter some information from the puck any of the numbers must be pressed. If you want the program to calculate an area while you are digitizing points, you must enter the points defining the perimeter of the area in a clockwise fashion and close the figure. Closing the figure is done by entering the last point of the figure where you entered the first point. If you want to subtract some points digitized, move over the same line in a counter-clockwise direction. When you are using the 'area' function and the tablet is in the 'incr' mode you must continuously press any of the puck's number keys to send a continuous stream of points to the program. Just press a number on the puck for each point to be digitized when you are using the 'point' function and likewise for the 'length' function. [3!v