Compiling is the process by which COMPASS converts raw survey data into a form that can be displayed and manipulated. In the mathematical terms, the raw data is in polar coordinates and the process of compiling converts it to Cartesian coordinates. The process also involves analyzing how all the stations in the cave are connected together. The program has to be able resolve forward references, deal with loops, and back sights. In COMPASS, shots can be in order and the program will sort them out.
While the data is being processed, COMPASS analyzes the data for errors and generates a number of statistics that are useful to the understanding of the cave. COMPASS keeps track of 39 statistics and displays them in the following window:
The statistics display is made up of seven parts. All information can be displayed, printed, saved to a file or copied to the clipboard.
The data summary includes basic information like the length of the cave and number of shots. It also includes more exotic items like the volume of the cave and difficulty of the cave. Length measurements are displayed in meters, feet, miles and kilometers where appropriate. Here is a sample data summary for part of Lechuguilla Cave:
DATA SUMMARY for : Lech.mak ================================================================================ Number Of Files= 7 Station Aliases= 0 Number Of Surveys= 2055 Number Of Stations= 25798 Included Shots= 27045 Excluded Shots= 606 Ignored Shots= 231 Number Of Loops= 1849 Absolute Stations= 0 Purged Stations= 0 -------------------------------------------------------------------------------- Included Length= 584395.6 Feet 178123.8 Meters 110.68 Miles Excluded Length= 18871.3 Feet 5752.0 Meters Total Surveyed= 603266.9 Feet 183875.7 Meters 114.26 Miles Horizontal Length= 517109.3 Feet 157614.9 Meters 97.94 Miles Horizontal Excluded= 17617.0 Feet 5369.7 Meters Cave Depth= 1604.2 Feet 489.0 Meters Surface Length= 10900.1 Feet 3322.4 Meters Surface Width= 4887.7 Feet 1489.8 Meters Surface Area= 53276348.0 Ft^2 4949534.7 M^2 Enclosed Volume= 85466573022.7 Ft^3 2420143837.0 M^3 Cave Volume= 2752350173.1 Ft^3 77937877.6 M^3 Average Diameter= 68.6 Feet 20.9 Meters Wall Area= 126674733.2 Ft^2 11768467.8 M^2 Floor Area= 51779254.5 Ft^2 4810450.1 M^2 Volume Density= 3.22 % Average Inclination= 21.4 Deg. Difficulty= 19.0 -------------------------------------------------------------------------------- Highest Station= TA34 26.3 Feet 8.0 Meters Lowest Station= DIVE -1577.9 Feet -481.0 Meters North Most Station= CF28 672.2 Feet 204.9 Meters South Most Station= JJ7 -4215.5 Feet -1284.9 Meters East Most Station= MAX29 5227.3 Feet 1593.3 Meters West Most Station= N49 -5672.8 Feet -1729.1 Meters -------------------------------------------------------------------------------- Average Shot Length= 21.6 Feet 6.6 Meters Longest Shot= 216.7 Feet 66.1 Meters Shortest Shot= 0.4 Feet 0.1 Meters -------------------------------------------------------------------------------- |
This item lists all the survey stations in the cave and the cartesian coordinates. This is useful for locating stations, for hand drawing maps on a grid and for import into other programs. Here is a sample set of coordinates:
Station COORDINATES: Index Station Parent east north vertical =============================================================================== 0 F1 Ent 0.000ft 0.000ft 0.000ft 1 F2 F1 -12.649ft -91.038ft 4.013ft 2 F3 F2 -56.783ft -123.803ft 2.094ft 3 F4 F3 -64.474ft -182.943ft -1.554ft 4 F5 F4 -90.532ft -219.597ft -3.125ft 5 F6 F5 -82.638ft -283.069ft -0.891ft |
The coordinates are the East, North and Vertical distance from the cave entrance or other fixed or georeferenced stations. The parent station is the first station that connects to a station and first defines its locations.
When loop fails to close, the errors indicate the cumulative quality of the shots in the loop. Thus the loop errors are indication of the quality of the survey and are useful for locating blunders. Here are some sample errors:
Closure Errors:
From To: north east vert. vector length percent
===================================================================================
F36 F22 3.87ft 1.37ft -10.66ft 11.43ft 113.20ft 10.09%
EXPECTED VALUES = 1.38ft 1.18ft 1.71ft 2.49ft 2.20%
STANDARD DEV. = 2.80 1.16 6.25 4.58
-----------------------------------------------------------------------------------
F41 F17 14.44ft -3.55ft -1.24ft 14.92ft 164.60ft 9.07%
EXPECTED VALUES = 1.31ft 2.10ft 2.40ft 3.45ft 2.09%
STANDARD DEV. = 11.05 1.69 0.52 4.33
-----------------------------------------------------------------------------------
|
The error is displayed in several ways. First it is broken down into its north, east and vertical components. This is helpful for isolating the source of the error. For example, if the majority of the error is vertical, it implies that the majority of the errors are in the inclination readings. Next the error is displayed as the length of the error vector.
The most useful method of evaluating a loop is to compare it to the kind of error you would expect to get if all the errors are random. The program analyzes every shot in a loop and makes a prediction about the size of error you expect to find if the errors were random. These values give the expected standard deviation for the loop and they are Expect Values displayed above. These values are compared with the actual values and the ratio gives the number of standard deviations the errors represent. The higher the number, the worse the loop. Loops that exceed two standard deviations, have a high probability of having one or more blundered measurement.
The final number is the percentage error. This is calculated by dividing the error by the length of the loop. For example, a one foot error in a one hundred foot loop would give a one percent error. Percent error is a less useful measurement of loop quality because it does not take into account the number of shots, the quality of the instruments and the configuration of the loop.
This statistic list all the stations in each loop.
Stations Within Loops:
===============================================================================
Closure Is Between: F28A-F28
F28A,F28B,F30G,F30F,F30E,F30D
F30C,F30B,F30A,F30,F29,F28
Common point: F28
F28
Closure Is Between: FE28D-FE39
FE28D,FE28C,FE28B,FE28A,FE28
Common point: FE28
FE39,FE38,FE37,FE36,FE34,FE33
FE32,FE31,FE30,FE29,FE28
|
Loops are defined by closing shot, common point and two traverses. Each of the stations listed above are the path that defines a particular loop. This is information is useful for locating blunders.
This statistic extracts the sequences of station names that have been used in
the cave survey. This makes it easy to find out which station names have been
used and which are available for future survey work.
Station Sequences: ================================================================================ Page: 1 A(10-26)Red CB16(A-G) CH(17-18) CHJ(1-6) DE(1-10) A(1-14) CBA(1-5) CH(19-20)' CHK'(1-14) DFW(1-8) A(15-26)Blue CBR(1-5) CH(20-22) CHK'6A DFX(1-4) A(17-23) CBS(1-7) CH(2-3)' CHP(1-6) DFX4A A(28-32)Blue CBT(1-6) CH(23-31)' CHR(1-24) DG(1-11) A(28-32)Red CBZ(1-5) CH(3-7) CHS(2-3) DG(30-34) A(34-36)Blue CBZ1A CH(5-8)' CHS(2-3)A DIVE A(34-36)Red cc(1-4) CH(9-12) CHS(4-5)' DR(1-16) A(4-5)Red CC(1-6) CH1 CHS(5-16) DR14A A(7-13)Blue CD(1-12) CH10(A-B) CHS3B DSM(1-11) A1(a-b) CE(1-17) CH14'(C-D) CHS5'(A-C) DZ(1-5) A1Blue CE(3-4)' CH18(A-F) CHS6(A-B) DZA(1-4) A21(a-b) CE(7-8)' CH25 CHS8A E(1-27) A23A CE3(B-G) CH7(A-E) CHT(1-5) E14(A-B) A2Red CE3A CH8Z CHTA(1-21) E2(A-B) A5(a-f) CE3A' CHA(1-2)' CHTA6A E22(B-I) |
The option displays the base station name and the sequence associated with it. For example if the cave contains a sequence of stations that runs from A1 to A29, the sequence would show up in the list as A (1-29). The program can find both numeric and alphabetic sequences and is capable of picking out the changing part of the name even if it is in the middle of the name. It also handles interrupted and partial sequences.
If COMPASS encounters a shot where both stations have not been previously seen, it cannot tie the shot into the rest of the cave. Usually, these shot will tie into the cave later after other surveys are processed. This situation is called a Forward Reference, because the shot refers to a station that will be defined in the future. COMPASS handles this situation by saving these shots until later. These saved shots are called Suspended Shot and you can display a list of all shots that were suspended during the processing of the data. This information can be useful for reorganizing the data for optimal processing.
Suspended Stations: Index From To From Par To Par Connected =============================================================================== 0 FRB5 FRC1 FRB4 FRB5 Yes 1 FRC1 FRC2 FRB5 FRC1 Yes 2 FRC2 FRC3 FRC1 FRC2 Yes 3 FR18 FRB1 FR17 FR18 Yes 4 FRB1 FRB2 FR18 FRB1 Yes 5 FRB2 FRB3 FRB1 FRB2 Yes |
The data shows the From and To station of each shot and the "parents" of the stations. It also shows whether the shot ultimately connected to the cave. If a shot doesn't connect to the cave, the program will also give an error message.
This item displays statistics for individual surveys. It shows the number of shots in each survey, the length of the survey and the average shot length..
Surveys: Index Survey Length Shots Ave. Len. =============================================================================== 0 F 1971.2ft 61 32.3ft 1 FA 93.0ft 3 31.0ft 2 FB 534.0ft 14 38.1ft 3 FC 283.1ft 11 25.7ft 4 FBB 1190.2ft 28 42.5ft 5 FE 1906.1ft 67 28.4ft 6 FKK 3174.7ft 60 52.9ft |
The final item displays an alphabetically sorted list of all surveys in the cave. This is useful for keep track of survey names that have been used and to keep from assigning duplicate names. It is also useful for general record keeping.
