Hi,
I have two questions :
1- What are the parameter dX, dY and dZ in the Datums?
2- I have several .tif maps with their associated world file. Is there any way to create .cal files without having to import all maps manually? All maps that I need to import have the same utm zone and datum.
Thanks
Franco
Hi,
there is some knowledge required about what maps (internal formats) you realy have there.
- a tfw file is not sufficient to import calibrated, as a *.tfw file does by far not
hold all parameters required for georeferencing.
- sometimes files that come with a *.tfw file are in fact geotiff files, which
include in an internal header all information required to be imported calibrated.
To import maps that come with a *.tfw only:
- start TTQV, set the correct units (map datum, ....) in TTQV-units.
- import using the cd-rom icon in ttqv-xplorer menu
or
- do a single map import
TTQV will use the parameters you have already set. You have to know
about the map datum, the projection, respectively the national meter grid
used when the *.tfw was created.
If the files are realy geotiff, TTQV will import them calibrated if it knows
the units used (known for the more common units)
You have to use an up to date version of TTQV, best would be to use the
latest development releas of TTQV3, here:
http://www.ttqv2.de/files9/qv3upd_100.exe
hint:
In case you open whatever geotiff file in a raster software (paintshop,
photoshop....) and save it, all internal geotiff informations will be gone.
Hi,
Zitat von "Franco"1- What are the parameter dX, dY and dZ in the Datums?
oups, I did forget this one !
These are shifting parameters, which describe a part of the offset of any
local map datum in comparison to WGS84. For extensive information,
see here:
http://www.colorado.edu/geogra…ft/notes/datum/datum.html
Zitat von "jockel"Alles anzeigenHi,
oups, I did forget this one !
These are shifting parameters, which describe a part of the offset of any
local map datum in comparison to WGS84. For extensive information,
see here:
http://www.colorado.edu/geogra…ft/notes/datum/datum.html
But is it possible to set this parameters in QV3 and/or how?
Hi,
Zitat von "damjang"....But is it possible to set this parameters in QV3 and/or how?
why do you thin this is necessary? These parameters are part of a given
map-datum. All usual map-datums are already available in TTQV2, no need
to specially create them.
In case you realy need a new/different map-datum, you can create it in
QV-Xplorer, QV-System, Datums
Zitat von "jockel"Alles anzeigenHi,
why do you thin this is necessary? These parameters are part of a given
map-datum. All usual map-datums are already available in TTQV2, no need
to specially create them.
In case you realy need a new/different map-datum, you can create it in
QV-Xplorer, QV-System, Datums
I have to set an Italian datum, but without this 3 parameters (like the one available by default) the error in conversion is more than 20-30 meters. I don't know if there it is another way to do the same conversion without this errors...
Franco,
Zitat von "damjang"I have to set an Italian datum, but without this 3 parameters (like the one available by default) the error in conversion is more than 20-30 meters. I don't know if there it is another way to do the same conversion without this errors...
What Datum are you talking about exactly, post the parameters here
and I can check whether it is already built in, as there are:
dx, dy, dz, radius, 1/f (respectively ellipsoid in use)
Zitat von "jockel"Franco,
What Datum are you talking about exactly, post the parameters here
and I can check whether it is already built in, as there are:
dx, dy, dz, radius, 1/f (respectively ellipsoid in use)
Sorry, I make a mistake :crazy: ! The dX, dY and dZ parameters are all ok. I use the "Rome 1940" datum with the "Italy, Gauss Boaga, Zone 2 East" National Grid. With this settings there was an error of 10m in N and 2m in E. This because Rome 1940 datum need another two parameters, Correction in N and Correction in E. This two parameters are two values that are add to the original WGS84 position to "correct" the result. I have tested it with 3 and 7-parameters conversion. The two parameters are: CorrectionN=+0,325"N(seconds N) and CorrectionE=+0,094"E. If I made this correction manualy befor conversion in QV the resulting position is OK.
I think that there will be usefull if QV have the possibility to set this two parameters too.
Eg. for a position:
WGS84: 45,71434 - 13,720567
ok convertion in Gauss-Boaga: 5063128 - 2420428
and with QV: 5063118 - 2420426 (10m and 2m error)
Regards
damjang
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