[Qgis-user] Georeferencing a geotiff issues.

[Michael Dufty]

Has anyone been able to successfully use the georeferencer to adjust alignment 
on a geotiff that already has positioning data?
I've been trying to make some minor adjustments to some drone generated mosaics.
My experience is the georeferencer seems to correctly load the geotiff with CRS.
It displays the projected coordinates and records GCPs in those coordinates, 
but it appears to then try to transform as though they were pixel coordinates.
Eg. the Source and destination GCP's Y values might be 6,300,000 and 6,300,010  
but the dy reported is not 10, it is approximately -6,300,000
If I ignore the problem the georeferencer runs correctly, but puts the result 
completely in the wrong place as suggested by the dy value.
This is happening with source, control points and destination CRS all set the 
same.

Is there something I am doing wrong or is this just a bug?  Seems to work fine 
if I run the geotiff through and image editor to remove the initial 
georeferencing.

Michael Dufty

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Re: [Qgis-user] Does DWG work in 3.22? - RE: importing dwg/dxf

[Michael Dufty]

The older version of AutoCAD Civil3d I have includes AutoCAD map functions and 
definitely gives you options to include CRS information in the dwg outputs.  
The problem is I think the same software is the only thing that will read that 
information, so I never bothered using that function.The export to shape 
file feature is more useful.  Not sure how many versions of AutoCAD have that 
capacity, but I can't recall ever receiving any shape exports from AutoCAD.

Recent versions of QGIS seem to be handling dxf files really well, so I always 
convert to that before trying to open.  CADWizz is a very affordable converter 
that often seems to work when other options fail.

Michael Dufty

From: Qgis-user  On Behalf Of Jeff Sonnentag
Sent: Monday, 22 November 2021 12:07 PM
To: Bernd Vogelgesang ; Nicolas Cadieux 
; Greg Troxel ; Boaz Bar Ilan 

Cc: qgis-user 
Subject: [Qgis-user] Does DWG work in 3.22? - RE: importing dwg/dxf

Somebody must get the same quality of “engineering” that we do here.  :D

The last item received was in feet and aligns with California State Plane Zone 
6, but they chopped off the first digit of both “X” and “Y” for everything.  
Who knows why.  Maybe things run faster for them with 6 digit coordinates 
rather than 7 digit ones like you mentioned.  (???)

Anyway, when I tried the simple drag and drop into QGIS 3.22 it never worked.  
Always an error message about invalid data, even after I used DWG Trueview to 
convert it to the oldest possible versions (97/98 and 2000).  I did manage to 
get it in AFTER converting the DWG to a DXF with an online conversion site.  
That DXF could be drug (I hate the word “dragged” – seems along the lines of 
“runned”) into QGIS and appeared OK.  Export to a shapefile and then do some 
affine adjustment magic and things can be worked with.

Is there a reason that a DWG can’t be dropped into QGIS 3.22 but a DXF can?  
Are there some DWG versions that just don’t work?  I thought I got a DWG to 
appear OK in 3.16, but maybe I just imagined it and used a DXF before too. . . .


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[Qgis-user] Does DWG work in 3.22? - RE: importing dwg/dxf

[Jeff Sonnentag]

Somebody must get the same quality of “engineering” that we do here.  :D

The last item received was in feet and aligns with California State Plane Zone 
6, but they chopped off the first digit of both “X” and “Y” for everything.  
Who knows why.  Maybe things run faster for them with 6 digit coordinates 
rather than 7 digit ones like you mentioned.  (???)

Anyway, when I tried the simple drag and drop into QGIS 3.22 it never worked.  
Always an error message about invalid data, even after I used DWG Trueview to 
convert it to the oldest possible versions (97/98 and 2000).  I did manage to 
get it in AFTER converting the DWG to a DXF with an online conversion site.  
That DXF could be drug (I hate the word “dragged” – seems along the lines of 
“runned”) into QGIS and appeared OK.  Export to a shapefile and then do some 
affine adjustment magic and things can be worked with.

Is there a reason that a DWG can’t be dropped into QGIS 3.22 but a DXF can?  
Are there some DWG versions that just don’t work?  I thought I got a DWG to 
appear OK in 3.16, but maybe I just imagined it and used a DXF before too. . . .


From: Qgis-user  On Behalf Of Bernd 
Vogelgesang
Sent: Sunday, November 21, 2021 10:53 AM
To: Nicolas Cadieux ; Greg Troxel 
; Boaz Bar Ilan 
Cc: qgis-user 
Subject: Re: [Qgis-user] importing dwg/dxf


On 21.11.21 15:35, Nicolas Cadieux wrote:
Hi,

.dwg or dxf have no CRS.  They can be in inches, feet, mm, cm, m... Usually 
meter in a local CRS like a local WGS84 UTM ZONE is used.  You can usually find 
this in the metadata if available.

Nicolas

I have no deep technical insight into dwg or dxf, but I am pretty sure that 
those  CAD-"products" are able to be produced with valid coordinates, fitting 
to a common CRS. Most people using CAD-systems simply seem to be either too 
stupid for that, or just do not care.

One of the reasons, CAD-"data" is produced with a local reference system 
instead with a normal CRS is, according to an CAD-operator I once asked about 
this, that some CAD-systems just slow down to in-operability when using 
real-world coordinates because of the huge numbers, compared to the small 
coordinates in their own system.

So, I would not even try to fix this, but instead ask those guys to stop 
scratching their balls and better send you proper real-world data and tell you 
which CRS they are in . The handling of this "data" is punishment enough 
afterwords.

Hope my dislike for this "technology" was not too obvious ;)

Cheers,

Bernd



On 2021-11-21 9:07 a.m., Greg Troxel wrote:

Boaz Bar Ilan  writes:


i always have problem importing dwg or dxf .  the layers  dont fit the
coardinations and even when i set the layers crs it doesnt work.
I am far from an expert, but recently tried to deal with a dwg.

My impression is that they are almost always in local coordinates, and
the path to success is something like using GeoScience plugin to define
a local CRS based on control points where you know global coordinates
and local, and then to use that CRS for the data.

I recently imported some "PNEZD" data (csv with point it, northing,
easting, vertical, and description, all in an unspecified local grid,
from a total station data collector) and used geoscience to align it
wtih RTK obsservations of a few points, and things fit quite well.

How are you getting dwg?  Are you using the proprietary dwg library with
gdal, or is there some open source path?

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Re: [Qgis-user] importing dwg/dxf

[Richard Greenwood]

Any AutoCAD drawing *can* be on real world coordinates. They're often not
because no real world coordinates were readily available for the project
and there wasn't a compelling need for real world coordinates. AutoCAD
Map3D and subsequent versions with different names like "Civil 3D" have
support for coordinate system conversions, but that doesn't mean that a
DWG/DXF that was produced in vanilla AutoCAD can't be on a real world
coordinate system.

AutoCAD is always Cartesian projected coordinates (not spherical geography)
so you can open a DXF into a QGIS project and then use the QGIS move tool
to move it onto whatever reference data you have in the project. The
AutoCAD data might be in different units that you need but you can take a
guess and use the QGIS scale tool. A common problem in the USA is an
AutoCAD file that's in inches but your project is in feet. So scaling by 12
fixes that. And QGIS has a rotate tool that allows for aligning
different "norths". So with the three QGIS tools move, scale and rotate you
can do an affine transformation. Maybe not as accurate or as clean as you
might hope for, but it's a solution that I've used many many times.

On Sun, Nov 21, 2021 at 11:59 AM Nicolas Cadieux <
njacadieux.git...@gmail.com> wrote:

> Hi,
>
> Only AutoCAD Map3D was a certain comprehension of what a CRS is.  To my
> knowledge all other Autodesk Pilotdo not used any CRS.  It is my honest
> opinion that AutoCAD Map is the worst attempt to make a GIS.
>
> Nicolas Cadieux
> https://gitlab.com/njacadieux
>
> Le 21 nov. 2021 à 13:52, Bernd Vogelgesang  a
> écrit :
>
> 
> On 21.11.21 15:35, Nicolas Cadieux wrote:
>
> Hi,
>
> .dwg or dxf have no CRS.  They can be in inches, feet, mm, cm, m...
> Usually meter in a local CRS like a local WGS84 UTM ZONE is used.  You can
> usually find this in the metadata if available.
>
> Nicolas
>
> I have no deep technical insight into dwg or dxf, but I am pretty sure
> that those  CAD-"products" are able to be produced with valid coordinates,
> fitting to a common CRS. Most people using CAD-systems simply seem to be
> either too stupid for that, or just do not care.
>
> One of the reasons, CAD-"data" is produced with a local reference system
> instead with a normal CRS is, according to an CAD-operator I once asked
> about this, that some CAD-systems just slow down to in-operability when
> using real-world coordinates because of the huge numbers, compared to the
> small coordinates in their own system.
>
> So, I would not even try to fix this, but instead ask those guys to stop
> scratching their balls and better send you proper real-world data and tell
> you which CRS they are in . The handling of this "data" is punishment
> enough afterwords.
>
> Hope my dislike for this "technology" was not too obvious ;)
>
> Cheers,
>
> Bernd
>
>
>
> On 2021-11-21 9:07 a.m., Greg Troxel wrote:
>
> Boaz Bar Ilan   writes:
>
> i always have problem importing dwg or dxf .  the layers  dont fit the
> coardinations and even when i set the layers crs it doesnt work.
>
> I am far from an expert, but recently tried to deal with a dwg.
>
> My impression is that they are almost always in local coordinates, and
> the path to success is something like using GeoScience plugin to define
> a local CRS based on control points where you know global coordinates
> and local, and then to use that CRS for the data.
>
> I recently imported some "PNEZD" data (csv with point it, northing,
> easting, vertical, and description, all in an unspecified local grid,
> from a total station data collector) and used geoscience to align it
> wtih RTK obsservations of a few points, and things fit quite well.
>
> How are you getting dwg?  Are you using the proprietary dwg library with
> gdal, or is there some open source path?
>
> ___
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-- 
Richard W. Greenwood
www.greenwoodmap.com
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Re: [Qgis-user] importing dwg/dxf

[Nicolas Cadieux]

Hi,

Only AutoCAD Map3D was a certain comprehension of what a CRS is.  To my 
knowledge all other Autodesk Pilotdo not used any CRS.  It is my honest opinion 
that AutoCAD Map is the worst attempt to make a GIS.

Nicolas Cadieux
https://gitlab.com/njacadieux

> Le 21 nov. 2021 à 13:52, Bernd Vogelgesang  a écrit 
> :
> 
>  
> On 21.11.21 15:35, Nicolas Cadieux wrote:
>> Hi, 
>> 
>> .dwg or dxf have no CRS.  They can be in inches, feet, mm, cm, m... Usually 
>> meter in a local CRS like a local WGS84 UTM ZONE is used.  You can usually 
>> find this in the metadata if available. 
>> 
>> Nicolas 
> I have no deep technical insight into dwg or dxf, but I am pretty sure that 
> those  CAD-"products" are able to be produced with valid coordinates, fitting 
> to a common CRS. Most people using CAD-systems simply seem to be either too 
> stupid for that, or just do not care.
> 
> One of the reasons, CAD-"data" is produced with a local reference system 
> instead with a normal CRS is, according to an CAD-operator I once asked about 
> this, that some CAD-systems just slow down to in-operability when using 
> real-world coordinates because of the huge numbers, compared to the small 
> coordinates in their own system.
> 
> So, I would not even try to fix this, but instead ask those guys to stop 
> scratching their balls and better send you proper real-world data and tell 
> you which CRS they are in . The handling of this "data" is punishment enough 
> afterwords.
> 
> Hope my dislike for this "technology" was not too obvious ;)
> 
> Cheers,
> 
> Bernd
> 
> 
> 
>> 
>>> On 2021-11-21 9:07 a.m., Greg Troxel wrote: 
>>> Boaz Bar Ilan  writes: 
>>> 
 i always have problem importing dwg or dxf .  the layers  dont fit the 
 coardinations and even when i set the layers crs it doesnt work. 
>>> I am far from an expert, but recently tried to deal with a dwg. 
>>> 
>>> My impression is that they are almost always in local coordinates, and 
>>> the path to success is something like using GeoScience plugin to define 
>>> a local CRS based on control points where you know global coordinates 
>>> and local, and then to use that CRS for the data. 
>>> 
>>> I recently imported some "PNEZD" data (csv with point it, northing, 
>>> easting, vertical, and description, all in an unspecified local grid, 
>>> from a total station data collector) and used geoscience to align it 
>>> wtih RTK obsservations of a few points, and things fit quite well. 
>>> 
>>> How are you getting dwg?  Are you using the proprietary dwg library with 
>>> gdal, or is there some open source path? 
>>> 
>>> ___ 
>>> Qgis-user mailing list 
>>> Qgis-user@lists.osgeo.org 
>>> List info:https://lists.osgeo.org/mailman/listinfo/qgis-user 
>>> Unsubscribe:https://lists.osgeo.org/mailman/listinfo/qgis-user 
>> 
>> 
>> 
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Re: [Qgis-user] importing dwg/dxf

[Bernd Vogelgesang]

On 21.11.21 15:35, Nicolas Cadieux wrote:

Hi,

.dwg or dxf have no CRS.  They can be in inches, feet, mm, cm, m...
Usually meter in a local CRS like a local WGS84 UTM ZONE is used.  You
can usually find this in the metadata if available.

Nicolas


I have no deep technical insight into dwg or dxf, but I am pretty sure
that those  CAD-"products" are able to be produced with valid
coordinates, fitting to a common CRS. Most people using CAD-systems
simply seem to be either too stupid for that, or just do not care.

One of the reasons, CAD-"data" is produced with a local reference system
instead with a normal CRS is, according to an CAD-operator I once asked
about this, that some CAD-systems just slow down to in-operability when
using real-world coordinates because of the huge numbers, compared to
the small coordinates in their own system.

So, I would not even try to fix this, but instead ask those guys to stop
scratching their balls and better send you proper real-world data and
tell you which CRS they are in . The handling of this "data" is
punishment enough afterwords.

Hope my dislike for this "technology" was not too obvious ;)

Cheers,

Bernd




On 2021-11-21 9:07 a.m., Greg Troxel wrote:

Boaz Bar Ilan writes:


i always have problem importing dwg or dxf .  the layers  dont fit the
coardinations and even when i set the layers crs it doesnt work.

I am far from an expert, but recently tried to deal with a dwg.

My impression is that they are almost always in local coordinates, and
the path to success is something like using GeoScience plugin to define
a local CRS based on control points where you know global coordinates
and local, and then to use that CRS for the data.

I recently imported some "PNEZD" data (csv with point it, northing,
easting, vertical, and description, all in an unspecified local grid,
from a total station data collector) and used geoscience to align it
wtih RTK obsservations of a few points, and things fit quite well.

How are you getting dwg?  Are you using the proprietary dwg library with
gdal, or is there some open source path?

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Re: [QGIS-it-user] qgis.org è out

[Marco Spaziani]

Ora (18:55) è tornato online

Il giorno dom 21 nov 2021 alle ore 18:48 Marco Spaziani <
spaziani.ma...@gmail.com> ha scritto:

> Comunico che alle 18:45 www.qgis.org è out. Sapete cosa sia successo?
>
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[QGIS-it-user] qgis.org è out

[Marco Spaziani]

Comunico che alle 18:45 www.qgis.org è out. Sapete cosa sia successo?
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Re: [Qgis-user] importing dwg/dxf

[Nicolas Cadieux]

Hi,

.dwg or dxf have no CRS.  They can be in inches, feet, mm, cm, m... 
Usually meter in a local CRS like a local WGS84 UTM ZONE is used.  You 
can usually find this in the metadata if available.


Nicolas

On 2021-11-21 9:07 a.m., Greg Troxel wrote:

Boaz Bar Ilan  writes:


i always have problem importing dwg or dxf .  the layers  dont fit the
coardinations and even when i set the layers crs it doesnt work.

I am far from an expert, but recently tried to deal with a dwg.

My impression is that they are almost always in local coordinates, and
the path to success is something like using GeoScience plugin to define
a local CRS based on control points where you know global coordinates
and local, and then to use that CRS for the data.

I recently imported some "PNEZD" data (csv with point it, northing,
easting, vertical, and description, all in an unspecified local grid,
from a total station data collector) and used geoscience to align it
wtih RTK obsservations of a few points, and things fit quite well.

How are you getting dwg?  Are you using the proprietary dwg library with
gdal, or is there some open source path?

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--
Nicolas Cadieux
https://gitlab.com/njacadieux
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Re: [Qgis-user] importing dwg/dxf

[Greg Troxel]

Boaz Bar Ilan  writes:

> i always have problem importing dwg or dxf .  the layers  dont fit the
> coardinations and even when i set the layers crs it doesnt work.

I am far from an expert, but recently tried to deal with a dwg.

My impression is that they are almost always in local coordinates, and
the path to success is something like using GeoScience plugin to define
a local CRS based on control points where you know global coordinates
and local, and then to use that CRS for the data.

I recently imported some "PNEZD" data (csv with point it, northing,
easting, vertical, and description, all in an unspecified local grid,
from a total station data collector) and used geoscience to align it
wtih RTK obsservations of a few points, and things fit quite well.

How are you getting dwg?  Are you using the proprietary dwg library with
gdal, or is there some open source path?


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[Qgis-user] importing dwg/dxf

[Boaz Bar Ilan]

i always have problem importing dwg or dxf .  the layers  dont fit the
coardinations and even when i set the layers crs it doesnt work.

 does someone know how to do it ?

boaz
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