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DTI2DEM is a utility to convert data from a Laserscan Digital Terrain Image (DTI) file to a United States Geological Survey (USGS) Digital Elevation Model (DEM) of the same area.
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$ DTI2DEM DTI-file-spec [DEM-file-spec]
Command qualifiers Defaults /[NO]REWIND /NOREWIND /HEIGHT = unit /HEIGHT = METRES /PLAN = unit /PLAN = METRES /BLOCK = integer /BLOCK = 4096
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Input-DTI-file-spec
- specifies the input DTI file. Any part of the file specification which is not supplied will be taken from the default specification: 'LSL$DTI:.DTI;0'.
Output-DEM-file-spec
- is optional and specifies the output DEM file. If a disk file is specified it will be parsed against the default name: SYS$DISK:'file-spec'.DEM;0. If a tape device name is given output will be to that device which must have a tape mounted (/FOREIGN) on it. If missing the default is to write to the tape drive specified by the logical name MT:.
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/REWIND
/NOREWIND (default)
- If a tape drive is specified for the output DEM then the tape is rewound if this switch is specified. The default is to leave the tape at the current position
/HEIGHT = unit (default = METRES)
- Specifies the units for the elevation data in the DTI file. The choices are metres (the default), meters or feet.
/PLAN = unit (default = METRES)
- Defines the units of the ground coordinates in the DTI file. The choices are metres (the default), meters or feet.
/BLOCK = integer (default = 4096)
- Specifies the size of the physical blocks on the DEM tape. The value must be in the range 1024 - 8192 in steps of 1024 bytes. The default is 4096 byte blocks.
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When the command line has been processed, the input file has been opened and the output file opened or tape initialised then the user is prompted for more information. The three pieces of information that are required are:-
The input DTI file may not contain any information about its origin (if a projection record is not present) and therefore the user is asked to input the Eastings and Northings of the origin.
These may either be entered on separate lines, in response to the "Eastings Northings:" and "Northings:" prompts, or they may both be entered on the same line in response to the "Eastings Northings:" prompt.
The origin of the DTI file must lie on a 30 metre UTM grid intersection. If the header type is LSLA and a projection record is present then the user may respond with a carriage return and the origin is taken from the DTI header.
The DEM is bounded by the neat line of a 7.5-minute 1:24000 map sheet, and it is the SW corner of this sheet that must be entered in response to this prompt.
Both the latitude and longitude must be entered on the same line, but the order in which they occur is immaterial.
The format for each is d[ m[ s]]H
where "d" are integer degrees, "m" integer minutes , "s" integer seconds and "H" is a letter distinguishing the hemisphere (either S or N for latitude or E or W for longitude)
The values entered must correspond to a 7.5-minute graticule intersection.
If the area covered by the DTI file does not include the area required by the DEM area, then a warning message is output, and the program prompts for a new DTI origin.
This prompt allows the user to specify the header for the DEM (up to 144 ASCII characters).
If the operator responds with a carriage return, then the default of the DTI file name is used.
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DTI2DEM is a utility to convert a Laser-Scan Digital Terrain Image (DTI) file to the United States Geological Survey (USGS) Digital Elevation Model (DEM) format.
The coverage of the DEM is 7.5-minutes (1:24000 scale). 1-degree coverage DEM's are not currently supported.
The input DTI file can have any header type currently supported by DTILIB. The recommended header type is LSLA.
Output is either to an ASCII sequential disk file, with a record length of 1024 characters, or to an unlabelled magnetic tape, written at a density of 1600 bpi, with a record size of 1024 characters and a block size that can be selected by the user (default 4096 characters).
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User input is represented in bolface
$ DTI2DEM LSL$SOURCE_ROOT:[USBUR.DTI2DEM]ZYCOR ZYCOR <CR>
%DTI2DEM-I-DTIHDRTYP, Input DTI file has header type MIKE File : LSL$SOURCE_ROOT:[USBUR.DTI2DEM]ZYCOR.DTI; Header : MIKE Data: WORD Units are metres Matrix Coverage SW: 0.00 0.00 NE: 10020.00 13890.00 Matrix Interval E: 30.00 N: 30.00 Value Range :-32767 to 2686 Define origin of the DTI (in UTM coordinates) (default: 0.0 0.0) Eastings Northings: 529890 4899510 Enter lat and long of SW corner of map (eg 39 07 30N 77 22 30W) Latitude Longitude: 44 15N 74 37 30W Enter header for DEM file (ZYCOR): Scanning DTI file ZYCOR for max and min values Outputting DEM file to SYS$DISK:ZYCOR.DEM ...record 50 ...record 100 ...record 150 ...record 200 ...record 250 ...record 300 ELAPSED: 0 00:02:39.62 CPU: 0:01:21.66 BUFIO: 68 DIRIO: 292 FAULTS: 694
This example reads a DTI file with a MIKE type header and writes the output DEM to a disk file in the current default directory. The contents of the DTI header record are displayed before the user is prompted to input the origin of the DTI and the SW corner of the DEM. The default of the DTI filename is used as the DEM header by responding to the "Enter header for DEM file" prompt with a carriage return.
$ DTI2DEM VONORE VONORE <CR>
%DTI2DEM-I-DTIHDRTYP, Input DTI file has header type LSLA File : LSL$DTI:VONORE.DTI; Header : LSLA Data: WORD Units are metres Matrix Coverage SW: 749070.00 3931800.00 NE: 760770.00 3945990.00 Matrix Interval E: 30.00 N: 30.00 Value Range : 238 to 421 -DTI2DEM-I-PRJREC, Projection record found Spheroid : 0 (Clarke 1866) Projection : 1 (Universal Transverse Mercator) Zone : 16 Units : 2 (metres) Local origin : 749070.000 (Eastings) 3931800.000 (Northings) Sample values : 30.000 (Eastings) 30.000 (Northings) Define origin of the DTI (in UTM coordinates) (default: 749070.0 3931800.0) Eastings Northings: Enter lat and long of SW corner of map (eg 39 07 30N 77 22 30W) Latitude Longitude: 35 30N 84 15W Enter header for DEM file (VONORE): Scanning DTI file VONORE for max and min values Outputting DEM file to SYS$DISK:VONORE.DEM ...record 50 ...record 100 ...record 150 ...record 200 ...record 250 ...record 300 ...record 350 ELAPSED: 0 00:02:56.76 CPU: 0:01:32.71 BUFIO: 76 DIRIO: 472 FAULTS: 917
This example reads a DTI file with a LSLA type header and writes the output DEM to a disk file in the current default directory. The contents of the DTI header record and projection record are displayed before the user is prompted to input the origin of the DTI and the SW corner of the DEM. The origin of the DTI is taken from the DTI header by responding to the Eastings Northings prompt with a carriage return. The default of the DTI filename is used as the DEM header by responding to the "Enter header for DEM file" prompt with a carriage return.
$ DTI2DEM/REWIND/BLOCK=8192 VONORE MUB1: <CR>
%DTI2DEM-I-DTIHDRTYP, Input DTI file has header type LSLA File : LSL$DTI:VONORE.DTI; Header : LSLA Data: WORD Units are metres Matrix Coverage SW: 749070.00 3931800.00 NE: 760770.00 3945990.00 Matrix Interval E: 30.00 N: 30.00 Value Range : 238 to 421 -DTI2DEM-I-PRJREC, Projection record found Spheroid : 0 (Clarke 1866) Projection : 1 (Universal Transverse Mercator) Zone : 16 Units : 2 (metres) Local origin : 749070.000 (Eastings) 3931800.000 (Northings) Sample values : 30.000 (Eastings) 30.000 (Northings) Define origin of the DTI (in UTM coordinates) (default: 749070.0 3931800.0) Eastings Northings: Enter lat and long of SW corner of map (eg 39 07 30N 77 22 30W) Latitude Longitude: 84 15W 35 30N Enter header for DEM file (VONORE):VONORE TENNESSEE TN- 84 15 W 35 30N (DTI2DEM 1-Nov-1989) Scanning DTI file VONORE for max and min values Outputting DEM file to _LSLM3A$MUB1: ...record 50 ...record 100 ...record 150 ...record 200 ...record 250 ...record 300 ...record 350 ELAPSED: 0 00:05:57.93 CPU: 0:01:36.08 BUFIO: 17 DIRIO: 409 FAULTS: 399
This has the same input file as the previous example but the output is directed to the tape on drive MUB1:. The DTI origin is taken from the DTI header. A descriptive DEM header is entered which describes the map and how it was produced.
See dti2demmsg.html generated from DTI2DEMMSG.RNO.