XYZ files of airborne VTEM system

XYZ files contain transient responses recorded by a Geotech helicopter VTEM time-domain electromagnetic system. The files can be exported from Geosoft Oasis Montaj database (.gdb) and are supplied to clients by Geotech after field surveys, together with the gdb database.


Example file

/ ------------------------------------------------------------------------------
/ XYZ EXPORT [04/08/2014]
/ DATABASE   [265_final.gdb]
/ ------------------------------------------------------------------------------
/
/          x            y    Longitude    Latitude      DEM     radarb     SFz[0]    SFz[1]    SFz[2]    SFz[3]    SFz[4]    SFz[5]    SFz[6]    SFz[7]    SFz[8]    SFz[9]   SFz[10]   SFz[11]   SFz[12]   SFz[13]   SFz[14]   SFz[15]   SFz[16]   SFz[17]   SFz[18]   SFz[19]   SFz[20]   SFz[21]   SFz[22]   SFz[23]   SFz[24]   SFz[25]   SFz[26]   SFz[27]   SFz[28]   SFz[29]   SFz[30]   SFz[31]   SFz[32]   SFz[33]   SFz[34]   SFz[35]   SFz[36]   SFz[37]   SFz[38]   SFz[39]   SFz[40]   SFz[41]   SFz[42]   SFz[43]   SFz[44]   SFz[45]   SFz[46]   SFz[47]   SFz[48]   SFz[49]     
/=========== ============ ============ =========== ======== ========== ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= ========= =========  
/
//Flight 10
//Date 2013/07/25
Line  1000
   538990.1    4924671.1   -98.382040   55.547016    310.6       40.7         *         *         *         *         *         *         *         *         *         *         *         *         *         *   9.88349   6.23418   3.55503   1.85807   0.88574   0.40123   0.18278   0.09416   0.04886   0.02950   0.01805   0.00996   0.00603   0.00294   0.00225   0.00351   0.00074   0.00060   0.00127   0.00073   0.00031  -0.00044  -0.00005   0.00093   0.00082   0.00040   0.00006  -0.00053   0.00055  -0.00040   0.00075  -0.00083         *         *         *         *   
   538991.3    4924669.6   -98.382021   55.546998    310.7       40.7         *         *         *         *         *         *         *         *         *         *         *         *         *         *   9.91786   6.25654   3.57171   1.86368   0.88773   0.40138   0.18183   0.09393   0.04878   0.02926   0.01782   0.01011   0.00583   0.00296   0.00210   0.00335   0.00075   0.00020   0.00136   0.00071   0.00027  -0.00045  -0.00004   0.00093   0.00093   0.00046   0.00009  -0.00042   0.00054  -0.00033   0.00070  -0.00082         *         *         *         *    
   538992.5    4924668.0   -98.382002   55.546980    310.7       40.6         *         *         *         *         *         *         *         *         *         *         *         *         *         *   9.95203   6.27506   3.58759   1.86879   0.88968   0.40164   0.18103   0.09371   0.04876   0.02901   0.01761   0.01028   0.00563   0.00299   0.00195   0.00322   0.00079  -0.00013   0.00145   0.00070   0.00023  -0.00046  -0.00003   0.00092   0.00103   0.00051   0.00012  -0.00024   0.00054  -0.00024   0.00066  -0.00080         *         *         *         *   
   538993.7    4924666.4   -98.381984   55.546962    310.7       40.5         *         *         *         *         *         *         *         *         *         *         *         *         *         *   9.98538   6.29043   3.60200   1.87334   0.89155   0.40198   0.18050   0.09349   0.04881   0.02876   0.01741   0.01044   0.00543   0.00304   0.00179   0.00310   0.00083  -0.00036   0.00152   0.00069   0.00018  -0.00047  -0.00002   0.00090   0.00112   0.00056   0.00015   0.00001   0.00054  -0.00014   0.00062  -0.00077         *         *         *         *   
   538994.9    4924664.8   -98.381965   55.546945    310.8       40.4         *         *         *         *         *         *         *         *         *         *         *         *         *         *  10.01667   6.30357   3.61425   1.87733   0.89329   0.40240   0.18032   0.09329   0.04891   0.02851   0.01725   0.01058   0.00524   0.00308   0.00164   0.00299   0.00086  -0.00049   0.00159   0.00070   0.00014  -0.00046  -0.00001   0.00089   0.00119   0.00059   0.00017   0.00031   0.00053  -0.00004   0.00058  -0.00074         *         *         *         *    
Line  1010
//a comment
   538996.1    4924663.2   -98.381946   55.546927    310.8       40.3         *         *         *         *         *         *         *         *         *         *         *         *         *         *  10.04461   6.31547   3.62373   1.88084   0.89484   0.40290   0.18054   0.09311   0.04905   0.02825   0.01712   0.01068   0.00505   0.00313   0.00148   0.00289   0.00090  -0.00052   0.00165   0.00070   0.00009  -0.00045  -0.00000   0.00087   0.00123   0.00061   0.00020   0.00063   0.00053   0.00005   0.00054  -0.00069         *         *         *         *    
   538997.3    4924661.7   -98.381928   55.546909    310.8       40.3         *         *         *         *         *         *         *         *         *         *         *         *         *         *  10.06809   6.32699   3.63012   1.88395   0.89615   0.40346   0.18114   0.09295   0.04923   0.02801   0.01702   0.01076   0.00488   0.00318   0.00132   0.00279   0.00092  -0.00047   0.00169   0.00071   0.00005  -0.00042   0.00001   0.00086   0.00124   0.00061   0.00023   0.00096   0.00053   0.00013   0.00050  -0.00065         *         *         *         *   
   539020.8    4924630.0   -98.381562   55.546551    309.9       39.2         *         *         *         *         *         *         *         *         *         *         *         *         *         *   9.04761   5.73972   3.30846   1.74290   0.86343   0.40797   0.20019   0.10336   0.05678   0.03197   0.01909   0.00977   0.00405   0.00347   0.00053   0.00328   0.00118   0.00116   0.00000   0.00028  -0.00068   0.00045   0.00047   0.00240   0.00133  -0.00075   0.00069  -0.00018  -0.00039  -0.00014   0.00073  -0.00014         *         *         *         *   

Names of columns and new profile (e.g. Line 1000) are required. Columns in XYZ file may be of any number and order. Required columns for data input are:


--------------------
UNITS
Unit Types               : 0=mV, 1=uV, 2=nV, 3=pV, 4=nT, 5=pT, 6=fT, 7=ppmHp, 8=%Ht, 9=nT/A.s, 10=pT/A.s, 11=ppmHt, 12=pptHp, 13=pptHt, 14=ppmHx, 15=ppmHz, 16=pptHx, 17=pptHz
Units                    : 3
Normalise by Rx Area     : YES
Normalise by Tx Area     : YES
Normalise by Tx Current  : YES
--------------------
Fig. 1. A fragment of MCG file specifying EM signal dimension and normalization parameters.

If file lacks Longitude and Latitude columns, coordinates are taken from x and y columns present in any (even relative) coordinate system. In this case, select other in the Coordinate system menu, which will inactivate the Google Maps tab

Figure 2 shows data export from Geosoft database. Export only columns to be used for data loading (x, y, Longitude (Lon), Latitude (Lat), DEM (DTM), radarb (RxAlt) and SFz (SF, dBdt)), in any order except the time-ordered SFz columns. When exporting data, specify that column names are to be exported.

Geosoft Oasis Montaj database export to XYZ file.
Fig. 2. Geosoft Oasis Montaj database export to XYZ file.

A standard VTEM GEOTECH SFz dataset in the Geosoft database consists of 50 elements from the first gate (zero time) to 13.161 ms. The times not supplied to the client are left blank. For instance, in the case of full waveform, the SFz dataset begins at 4th element (0.018 ms) while elements 0-3 are left blank (marked by * symbol); otherwise, data begin at 14th element (0.09 ms) while 0-13 are left blank. In some cases late-time data are missing as well, depending on base operating frequency and pulse width. When loading VTEM data to TDEM Geomodel, specify the number (index) corresponding to the first channel (CHANNEL TIMES) in the mcg file. For more details see … . XYZ files exported from TDEM Geomodel lack blank elements, i.e., the first channel corresponds to SFz[0].

XYZ files obtained by export from Geosoft Oasis Montaj (.gdb) database lack information on station number and resistivity model. TDEM Geomodel automatically saves the columns STATION, RESISTIVITY, and THICKNESS to the exported files. See below an example exported XYZ file from TDEM Geomodel.


Example XYZ file exported from TDEM Geomodel

/ ------------------------------------------------------------- 
/  
/  
/ ------------------------------------------------------------- 
/  
/   Station   Latitude   Longitude     DEM SFz[0]  SFz[1]  SFz[2]   SFz[3]   SFz[4]   SFz[5]   SFz[6]   SFz[7]   SFz[8]   SFz[9]  SFz[10]  SFz[11]  SFz[12]  SFz[13]  SFz[14]  SFz[15]  SFz[16]  SFz[17]  SFz[18]  SFz[19]  SFz[20]  SFz[21]  SFz[22]  SFz[23]  SFz[24]  SFz[25]  SFz[26]  SFz[27]  SFz[28]  SFz[29]  SFz[30]  SFz[31]  SFz[32]  SFz[33]  SFz[34]  SFz[35]  SFz[36]  SFz[37]  SFz[38]  SFz[39]  SFz[40]  SFz[41]  SFz[42]  SFz[43]  SFz[44]  SFz[45]  SFz[46]  RESISTIVITY_1   PHICKNESS_1 RESISTIVITY_2   PHICKNESS_2 RESISTIVITY_3   PHICKNESS_3 RESISTIVITY_4   PHICKNESS_4 RESISTIVITY_5
/  ========   ========   =========   =====  =====   =====   =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====    =====   ============     =========  ============     =========  ============     =========  ============     =========  ============
/ 
// Siberia. Mapping of permafrost. 
//Date 2014 
Line 1 
          1     62.4587     113.761     383      *    1203   908.5    637.6    446.3    316.9    228.9    167.9    125.4    90.36    63.04    43.82    32.25     23.9    17.93    14.17    11.01    8.556    6.486    5.083    4.111    3.361    2.889    2.542    2.167    1.778        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *           54.3            25           500         205.2            34             *             *             *             *
          3     62.4579    113.7622     383   1869    1686    1165    787.2    537.3    375.3    267.6    193.6    142.7    101.8    69.82    47.79    34.62     25.1    18.59    14.37    11.03    8.296    6.271    5.196    4.511    3.869    3.338    2.682    2.151    1.746    1.299    1.254    1.108    1.094        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *           50.9            25           500         207.8          33.3             *             *             *             *
          4   62.457143  113.762859     383      *    1465    1147      821    577.7    407.8    290.5    209.3      153    107.7    73.15    49.97    36.58    27.12    20.73    16.81    13.55    10.82    8.192     6.37    5.212    4.308    3.757    3.305    2.811    2.274    2.076    1.737    1.624    1.667        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *           48.4            25           500         162.6          33.3             *             *             *             *
          7     62.4552     113.764     383      *       *       *        *    590.7    500.1    415.7    351.1    301.9    254.4    201.6    151.5    119.8    103.1    93.89    83.61     67.9    54.62    48.96    41.48    30.87    26.19    24.89    20.64    17.95    17.28    15.08    14.56    13.25    12.23    11.28     10.4    9.044    7.213        5    5.451    4.057    4.139    3.661    3.238    3.893    2.814    2.172    2.049    1.831    1.355    1.776           23.6            25           500          22.6           334          53.3           198          53.3          6.98
          8      62.455    113.7644     383      *       *       *        *    497.8    408.2      330    266.4    216.9      172    132.8    101.5    80.55    64.53    52.63    44.69    37.62     31.1    25.48    21.45    18.06    15.31    13.41    11.75    10.35    8.898    7.675    7.191    6.331     5.82    5.444     5.04    4.153    3.629     2.97    2.917    2.473    2.312        *        *        *        *        *        *        *        *        *           35.3            25           500          61.7          15.7             *             *             *             *
          9     62.4546    113.7642     383      *       *       *        *    503.9    434.9    364.1    298.8    246.9    197.2    153.5    118.6    95.59    77.67    63.48    54.01    45.91    38.13    30.99    26.06    22.41    19.23    16.83    14.77    13.17    11.53    10.05    9.019    7.903    6.989    6.237    5.806        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *           34.6            25           500          42.1          23.8             *             *             *             *
         10      62.454    113.7649     383      *    1338    1174    893.4    664.7    491.2      370    275.9    211.8    154.9    111.1    78.42    58.96    45.74    35.47    28.77    23.38    19.12    15.27    12.35    10.34     8.77    7.527    6.284    5.338    4.473    3.608    3.068    2.716    2.554        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *        *           38.1            25           500          77.9          34.6             *             *             *             *
         11     62.4539    113.7658     383      *       *     858    670.1    501.2    374.3    282.7    215.8    167.2    125.6       92    67.18    51.62    40.43    31.76    26.03    21.23    17.04    13.41    10.68    8.784    7.378    6.338    5.419     4.73    4.041    3.378    2.892      2.5    2.135    1.932    1.595    1.324        *        *        *        *        *        *        *        *        *        *        *        *        *        *           57.5          32.4           500          76.6          65.8             *             *             *             *
         12     62.4538    113.7667     383      *       *       *    611.7    437.4    313.4    229.3    172.3    133.1    100.8    75.34    56.71    44.78    35.91    28.78    23.84    19.69    15.95    12.67    10.17    8.352    6.994    6.035    5.134    4.434    3.661    2.832     2.26    1.888    1.673    1.573    1.399    1.137    0.878     0.72    0.769     0.55        *        *        *        *        *        *        *        *        *        *           51.7            25           500          80.8          79.5             *             *             *             *
         14     62.4537    113.7685     383      *       *    1020    705.9    494.2    355.8    263.1    199.4    154.9    117.6    87.82    66.04    52.12    41.55     33.2    27.58    22.65    18.34    14.33    11.31    9.223    7.485    6.296    5.335    4.466    3.674    3.003    2.485    2.027    1.677    1.428    1.221    1.046    0.911    0.713    0.516     0.49    0.469        *        *        *        *        *        *        *        *        *           41.2            25           500         133.7          42.9             *             *             *             *
         15     62.4531    113.7693     383      *       *   912.8    694.8    517.3    388.3    295.5    228.6    179.7    138.2    103.9    78.05    61.39    48.69    38.72    31.95       26    20.92     16.2    12.69    10.14    8.141    6.813    5.719    4.813    3.953    3.172    2.625    2.188    1.766    1.466    1.292    1.148        1    0.753    0.634        *        *        *        *        *        *        *        *        *        *        *           37.7            25           500         133.5          39.3             *             *             *             *
         16      62.453    113.7701     383      *       *   885.6    661.3    490.3    368.1    280.2    216.9    170.2    130.4    97.45    72.76    56.81    44.91     35.6     29.2    23.83    19.13    14.83    11.67    9.417    7.669    6.442    5.429    4.601    3.696    2.899    2.331    1.948    1.656    1.492    1.328    1.101    0.918     0.78    0.665    0.564        *        *        *        *        *        *        *        *        *        *           39.6            25           500         134.5            40             *             *             *             *
         18     62.4533    113.7713     383      *       *    1058    763.3    544.9    395.1    291.6    219.8    168.3    125.6    91.65    66.72    51.12    39.84    31.08    25.22    20.49    16.33    12.71    10.01    8.039    6.542    5.524    4.626    3.847    3.174    2.515    2.066    1.766    1.527     1.28    1.156    1.099    0.902    0.649    0.471     0.38    0.384    0.494     0.44    0.245    0.104    0.251    0.134        *        *        *           43.7            25           500         105.9          85.7             *             *             *             *

When saved to TDEM Geomodel, XYZ files are zipped together with MCG configuration files. The parameters STATION, RESISTIVITY, THICKNESS can be then reloaded to TDEM Geomodel.