Intersection Information

Use the INTERSCT GX to create an intersection table. Different statistics on intersection deviations can be calculated and saved to an output file.

Intersection Information dialog options

Input X channel

The input X channel.

Script Parameter: INTERSCT.InX

Input Y channel

The input Y channel.

Script Parameter: INTERSCT.InY

Input data channel

The input data channel.

Script Parameter: INTERSCT.InZ

Intersection tolerance

The intersection tolerance. This parameter is ignored if an existing intersection table is used as input.

  • The maximum limit can be set to 10 times the nominal sampling interval.

Script Parameter: INTERSCT.Tol

Tie lines or all lines

Select "All lines" or "Tie lines". This parameter is ignored if an existing intersection table or database is used as input.

Script Parameter: INTERSCT.Lines

Existing intersect table

The existing intersection table or database to get intersections from. If defined, then, instead of re-calculating the intersections from the database, they are read from this (table or database) file. For large databases, the time saved can be substantial.

Script Parameter: INTERSCT.OldTable

Output intersect table

The output intersection table/ database file name.

Script Parameter: INTERSCT.Table

Output statistics file

The output statistics file name. If specified, the statistics (minimum, maximum and standard deviation values) on the survey/tie line intersection deviations are reported in this output file. See Application Notes for more details.

Script Parameter: INTERSCT.StatsFile

Application Notes

The first step in leveling tie lines and regular survey lines is to produce a tie line intersection table or database.

Intersection Table Format (*.tbl)

The output intersection table file tabulates every intersection between tie lines and regular survey lines. It includes the exact ground location of the intersection point, the tie line and survey line numbers, the recorded value on each line, and the horizontal gradient of the data at that location. Following is an example of an intersection table:

/ Intersection Table
/
/ X Y Tie# TFid TZ TDZ Line# LFid LZ LDZ
8094.09 5336.51 90 1306.97 64180.2 0.068 470 574.133 64197.8 0.463
8106.99 1893.43 90 1409.55 64207.2 0.445 471 2276.95 64266.1 0.211
8049.27 7721.71 90 1030.20 64069.9 0.556 510 599.391 64065.8 0.155
8082.4 6688.47 90 1170.74 64116.5 0.421 490 2304.9 64130.0 0.526
7983.82 0078.85 90 777.000 64078.9 0.558 550 649.575 64069.6 1.376
8058.46 7854.91 90 876.391 64050.9 0.132 530 2282.74 64075.1 0.009
7997.32 2392.99 90 472.451 63904.9 0.759 590 881.501 63852.4 1.427
 

If the intersection tolerance is greater than 0.0, the points of closest approach within the tolerance will also be recorded, where lines do not actually intersect. The location will be the average of the closest points on each line.

The columns of the table are:

X

X coordinate of the intersection

Y

Y coordinate of the intersection

Tie#

Tie line number

TFid

Tie line fiducial

TZ

Tie line reading

TDZ

Tie line gradient (per fiducial)

Line#

Line number

Lfid

Line fiducial

LZ

Line reading

LDZ

Line gradient (per fiducial)


Intersection Database (*.gdb)

The Geosoft database can be used to store the intersections information. This has several benefits:

1. The exact intersections locations can be plotted to a map using the normal mapping and symbol methods.

2. Quantities such as the mis-tie or gradient values can be easily gridded for display.

3. Intersections are sorted by Tie Line, instead of appearing as a single long list.

To create an intersections database, simply run the Levelling Intersections GX and specify a file of type (*.GDB) as the output intersection table. The XLEVEL GX recognizes both the original *.tbl file format and the new Geosoft Database file as inputs. Each Tie in the intersection table gets its own line in the Geosoft Database file, containing all the line intersections with that tie line.

The channels of the intersection database are:

X

X coordinate of the intersection

Y

Y coordinate of the intersection

TIE

Tie line number

TIE_FID

Tie line fiducial.

TIE_LEVEL

Tie line reading.

TIE_GRAD

Tie line gradient (per fiducial).

LINE

Line number.

LINE_FID

Line fiducial.

LINE_LEVEL

Line reading.

LINE_GRAD

Line gradient (per fiducial)

Intersection_dX

Difference (at each intersection) between the closest X along the survey line and the closest X along the tie line.

Intersection_dY

Difference (at each intersection) between the closest Y along the survey line and the closest Y along the tie line.

Intersection_dDist

Distance (at each intersection) of the intersection deviations, calculated as:

Intersection_dData

Difference (at each intersection) between the closest data reading along the survey line and the closest data reading along the tie line.

CROSS_DIFF

Miss-tie value (LINE_LEVEL - TIE_LEVEL). Note that when the XLEVEL GX is used to extract mis-tie values to the flight database using the "Level Lines" option, the resulting CROSS_DIFF values in the flight database are of the opposite sign, i.e. TIE_LEVEL - LINE_LEVEL.

Intersection Statistics File

The following difference statistics (minimum, maximum and standard deviation values) on the survey/tie line intersection deviations are calculated and reported in the output file:

 

Min

Max

StdDev

X_Position

Intersection_dX_min Intersection_dX_max Intersection_dX_Dev

Y_Position

Intersection_dY_min Intersection_dY_max Intersection_dY_Dev

Distance

Intersection_dDist_min

Intersection_dDist_max

Intersection_dDist_Dev

Data

Intersection_dData_min

Intersection_dData_max

Intersection_dData_Dev

The XLEVEL GX can be used to extract levelling corrections from the intersection table. The STATLEV GX and the FULLLEV GX can then be used to apply the levelling corrections to the data.