[Gvsig_english] BUG: gvSIG 1.9 (Build 1253) Image Filtering
Simon Cropper (Botanicus Australia Pty Ltd)
scropper at botanicusaustralia.com.au
Thu Dec 17 14:18:13 CET 2009
Ben,
"Projection = a mathematical formula and its parameters that allows you to literally
project "natural" locations on the Earth's curved 3D surface to a plane for display on
e.g. a 2D map or monitor. An approximation model of Earth's geoid shape ("Ellipse") is
also needed for this to work."
OK... after you project the "natural" locations on the earths curved 3D surface to a plane what is the visual 2D representation called? Don't say projection. Whats its name? Are their multiple versions of this entity (depending on the creator)? How does this relate to lat-long?
Do you know of a good explanation of the "Datum + Projection + CRS = SRS" concept on the web (or can you provide one), so I can better understand the distinction between the various components?
Cheers Simon
Simon Cropper
Botanicus Australia Pty Ltd
PO Box 160, Sunshine, Victoria 3020.
P: 9311 5822. M: 041 830 3437.
mailto: scropper at botanicusaustralia.com.au
<mailto:scropper at botanicusaustralia.com.au>
web: www.botanicusaustralia.com.au <http://www.botanicusaustralia.com.au>
Benjamin Ducke wrote:
> A projection does just what the name says: it projects points from a
> 3D position on a curved surface to a 2D position on a cartesian
> (orthogonal) coordinate grid.
>
> Datum + Projection + CRS = SRS
>
> However, in most GIS user interfaces: SRS = Projection
>
> Ben
>
> ----- Original Message -----
> From: "Simon Cropper (Botanicus Australia Pty Ltd)" <scropper at botanicusaustralia.com.au>
> To: "Users and Developers mailing list" <gvsig_internacional at listserv.gva.es>
> Sent: Thursday, December 17, 2009 1:09:58 PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
> Subject: Re: [Gvsig_english] BUG: gvSIG 1.9 (Build 1253) Image Filtering
>
> Ben,
>
> So your definition of projection is limited to the visual 2D
> representation of a 3D sphere. Isn't this a datum-coordinate combo as I
> stated?
>
> Cheers Simon
>
> Simon Cropper
> Botanicus Australia Pty Ltd
> PO Box 160, Sunshine, Victoria 3020.
> P: 9311 5822. M: 041 830 3437.
> mailto: scropper at botanicusaustralia.com.au
> <mailto:scropper at botanicusaustralia.com.au>
> web: www.botanicusaustralia.com.au <http://www.botanicusaustralia.com.au>
>
>
>
> Benjamin Ducke wrote:
>
>> And here comes the artillery:
>>
>> Coordinate (reference) system (CRS) = a mathematical convention for describing locations relative
>> to a defined origin (e.g. Cartesian: 100m East, 200m North, Geographic: lat and long).
>>
>> Datum = a precise description of the origin of a geodetic system, nowadays this often includes
>> a mathematical transformation type and its parameters to convert measurements from
>> a foreign system into the system for which the datum is defined (e.g. Potsdam datum).
>>
>> Projection = a mathematical formula and its parameters that allows you to literally
>> project "natural" locations on the Earth's curved 3D surface to a plane for display on
>> e.g. a 2D map or monitor. An approximation model of Earth's geoid shape ("Ellipse") is
>> also needed for this to work.
>>
>> Spatial reference system (SRS) or geodetic reference system: the whole bunch of those
>> components together. This is what a GIS menu entry usually refers to, even if it is
>> labelled "projection".
>>
>> ... never mind what the GUIs tell you!
>>
>> Ben
>>
>>
>> ----- Original Message -----
>> From: "Simon Cropper (Botanicus Australia Pty Ltd)" <scropper at botanicusaustralia.com.au>
>> To: "Users and Developers mailing list" <gvsig_internacional at listserv.gva.es>
>> Sent: Thursday, December 17, 2009 12:49:06 PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
>> Subject: Re: [Gvsig_english] BUG: gvSIG 1.9 (Build 1253) Image Filtering
>>
>> Ben & Sergio,
>>
>> Thanks for your understanding. Feel a bit stupid now I look at the
>> dialog box. Pretty obvious when you have your head in gear.
>>
>> Ben. I'll bite. Enlighten me on the distinction between projection &
>> coordinate system.
>>
>> OK, here I go again, potentially making myself look stupid...
>>
>> coordinate system = northing-easting, lat-long (MGA55, AMG53)
>> datum = framework used to reference the coordinate system (GDA94, AGD66)
>> projection = particular datum-coordinate system combo (e.g. GDA94 MGA55,
>> GDA94 lat/long, AGD66 AMG53, etc)
>>
>> Should I duck for cover?
>>
>> Cheers Simon
>>
>> Simon Cropper
>> Botanicus Australia Pty Ltd
>> PO Box 160, Sunshine, Victoria 3020.
>> P: 9311 5822. M: 041 830 3437.
>> mailto: scropper at botanicusaustralia.com.au
>> <mailto:scropper at botanicusaustralia.com.au>
>> web: www.botanicusaustralia.com.au <http://www.botanicusaustralia.com.au>
>>
>>
>>
>> Benjamin Ducke wrote:
>>
>>
>>> It's OK Simon, we forgive you now ;)
>>>
>>> The problem with GIS is that the user interfaces are often designed
>>> by people who are not actually cartographers or geoscientists.
>>> Let's not even get started about the way the terms "projection"
>>> or "coordinate system" are used in GIS...
>>>
>>> Ben
>>>
>>> ----- Original Message -----
>>> From: "Simon Cropper (Botanicus Australia Pty Ltd)" <scropper at botanicusaustralia.com.au>
>>> To: "Users and Developers mailing list" <gvsig_internacional at listserv.gva.es>
>>> Sent: Thursday, December 17, 2009 12:16:47 PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
>>> Subject: Re: [Gvsig_english] BUG: gvSIG 1.9 (Build 1253) Image Filtering
>>>
>>> Ben,
>>>
>>> I agree. In cartographic terms it is correct. It should stay that way,
>>> but as you stated other packages don't express these ranges correctly
>>> and newbies to gvSIG, like myself, misunderstand the dialog box and post
>>> a thread. Some sort of reminder or warning right next to the input box
>>> would be a timely reminder.
>>>
>>> Cheers Simon
>>>
>>> Simon Cropper
>>> Botanicus Australia Pty Ltd
>>> PO Box 160, Sunshine, Victoria 3020.
>>> P: 9311 5822. M: 041 830 3437.
>>> mailto: scropper at botanicusaustralia.com.au
>>> <mailto:scropper at botanicusaustralia.com.au>
>>> web: www.botanicusaustralia.com.au <http://www.botanicusaustralia.com.au>
>>>
>>>
>>>
>>> Benjamin Ducke wrote:
>>>
>>>
>>>
>>>> Please keep it that way. It's perfectly correct in cartographic
>>>> terms. The fact that all other GIS have taught their users wrong
>>>> terminology does not change that.
>>>>
>>>> Ben
>>>>
>>>> ----- Original Message -----
>>>> From: "Sergio Clark" <sergio.clark at iver.es>
>>>> To: "Users and Developers mailing list" <gvsig_internacional at listserv.gva.es>
>>>> Sent: Thursday, December 17, 2009 9:58:23 AM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
>>>> Subject: Re: [Gvsig_english] BUG: gvSIG 1.9 (Build 1253) Image Filtering
>>>>
>>>> Hi,
>>>>
>>>> I don't think this is a bug. Now both raster and vector layers work the
>>>> same way regarding the scale range of visualization (we homogenized the
>>>> text in both pannels inside 'Properties').
>>>>
>>>> I mean, "Don't show layer when the scale is greater than 1:100" means
>>>> that it won't be displayed when scale is 1:99, because second one is
>>>> "greater scale" than first one (minor denominator, but major scale). And
>>>> it's the same for "less than...".
>>>>
>>>> Regards,
>>>> Sergio.
>>>>
>>>>
>>>>
>>>> Sergio Clark
>>>> Equipo gvSIG
>>>> IVER T.I., S.A.
>>>> www.iver.es
>>>> www.gvsig.com
>>>>
>>>>
>>>>
>>>> Rahkonen Jukka escribió:
>>>>
>>>>
>>>>
>>>>
>>>>> Hi,
>>>>>
>>>>> Maybe this is the old question about which scale is big and which is
>>>>> small? Compare scales 1:10 and 1:100. Hundred is bigger number than ten,
>>>>> but because it appears in the denominator the scale 1:100 is smaller
>>>>> than 1:10.
>>>>>
>>>>> Perhaps it would be more clear to put the words in another way: "Do not
>>>>> show this layer if scale denominator is bigger/smaller than".
>>>>>
>>>>> -Jukka Rahkonen-
>>>>>
>>>>> Simon Cropper wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> Hi Guys,
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> I have Noted a bug in the program.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> If you set the scale range for a raster file the "is above 1:????" and
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> "is below 1:????" is around the wrong way.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> If you set "Do not show this layer if the scale is above 1:100000",
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>> the
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> image only appears if the scale exceeds 1:100,000.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> So either the text is wrong or the filter condition is around the
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>> wrong way.
>>>>> _______________________________________________
>>>>> Gvsig_internacional mailing list
>>>>> Gvsig_internacional at listserv.gva.es
>>>>> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>> Este mensaje y sus archivos son confidenciales. No está permitida su reproducción o distribución sin la autorización expresa de "IVER Tecnologías de la Información". Si usted no es el destinatario previsto, queda desautorizado cualquier uso, acceso o copia de este mensaje. Si ha recibido este mensaje por error, por favor bórrelo e infórmenos por esta misma vía.
>>>>
>>>>
>>>> _______________________________________________
>>>> Gvsig_internacional mailing list
>>>> Gvsig_internacional at listserv.gva.es
>>>> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>>>>
>>>>
>>>>
>>>> ------
>>>> Files attached to this email may be in ISO 26300 format (OASIS Open Document Format). If you have difficulty opening them, please visit http://iso26300.info for more information.
>>>>
>>>> _______________________________________________
>>>> Gvsig_internacional mailing list
>>>> Gvsig_internacional at listserv.gva.es
>>>> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>>>>
>>>>
>>>>
>>>>
>>> _______________________________________________
>>> Gvsig_internacional mailing list
>>> Gvsig_internacional at listserv.gva.es
>>> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>>>
>>>
>>> ------
>>> Files attached to this email may be in ISO 26300 format (OASIS Open Document Format). If you have difficulty opening them, please visit http://iso26300.info for more information.
>>>
>>> _______________________________________________
>>> Gvsig_internacional mailing list
>>> Gvsig_internacional at listserv.gva.es
>>> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>>>
>>>
>>>
>> _______________________________________________
>> Gvsig_internacional mailing list
>> Gvsig_internacional at listserv.gva.es
>> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>>
>>
>> ------
>> Files attached to this email may be in ISO 26300 format (OASIS Open Document Format). If you have difficulty opening them, please visit http://iso26300.info for more information.
>>
>> _______________________________________________
>> Gvsig_internacional mailing list
>> Gvsig_internacional at listserv.gva.es
>> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>>
>>
> _______________________________________________
> Gvsig_internacional mailing list
> Gvsig_internacional at listserv.gva.es
> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>
>
> ------
> Files attached to this email may be in ISO 26300 format (OASIS Open Document Format). If you have difficulty opening them, please visit http://iso26300.info for more information.
>
> _______________________________________________
> Gvsig_internacional mailing list
> Gvsig_internacional at listserv.gva.es
> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>
More information about the Gvsig_internacional
mailing list