Re: [Qgis-user] z factor
Hi David, Thanks. Found this in my trash. Sorry for not responding sooner. I will look at the snippet It will be handy. So far, I have been using the plugin Builder and this https://www.qgistutorials.com/en/docs/3/building_a_python_plugin.html It's not up to date but it gives me a good idea of the procedure. I put the project aside this week but will probably get back to it next week. I have never programed a GUI before so that is my biggest issues for now. I should figure it out. Thanks again, Nicolas On 2020-11-27 4:04 p.m., David Strip wrote: And let us know how your experiment goes. I've thought about writing a plug-in, but never had a motivating problem. I did finally write a small snippet of code to add a new item to the file menu. The docs served well for the most part. - Attached file will add new File menu item to copy selected features from the current layer to a new memory layer. On Windows place this in C:\Users\account>\AppData\Roaming\QGIS\QGIS3 Presumably there's an obvious similar place on Macs and Linux. -- If you can, help others; if you cannot do that, at least do not harm them. /Dalai Lama/ -- Nicolas Cadieux https://gitlab.com/njacadieux ___ 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
Re: [Qgis-user] z factor
Hi, I did suggest it indeed. Ideally, it would go in the QGIS core every time they ask for a z factor. (Like under shading in the layer style). I will probably play around with it just to learn who to make a plugin but if you want to put it in your plugin, go ahead. Nicolas Cadieux https://gitlab.com/njacadieux > Le 27 nov. 2020 à 08:43, C Hamilton a écrit : > > > I have a Lat Lon Tools plugin, Field Calculator function that generates the > UTM zone. > > Nicolas, you just reminded me that you had suggested this to me earlier as a > plugin. Something like that would be easy to add, but I'm not sure it fits > within Lat Lon Tools which captures different coordinates, but z-factor is > related to the latitude so perhaps it fits. > > Does anyone think it would be worth adding to Lat Lon Tools or should it be a > separate plugin? > > Calvin > >> On Fri, Nov 27, 2020 at 4:52 AM Raymond Nijssen >> wrote: >> Hi Nicolas, >> >> It is just a simple formula for calculating the "z-factor" for a given >> latitude. What would that look like in a plugin? Where would it go? What >> would it do or show? >> >> Last week I had a similar idea for a plugin that could tell you which >> UTM zone to pick for your current canvas. I decided it would not be >> worth the effort. But maybe these could go together (and be finished at >> the end of this "KwakFriday"? >> >> Regards, >> Raymond >> >> >> On 27-11-2020 06:13, Nicolas Cadieux wrote: >> > Hi, >> > >> > It's just the Z factor needed when you make a hillshade when the x an y >> > are in degrees and the z is in feet or meters (like SRTM). You can see >> > it if you choose Hillshade under symbology / render type (for a raster >> > layer). It's basically the length of a degree in meters for latitude. >> > >> > https://www.esri.com/arcgis-blog/products/product/imagery/setting-the-z-factor-parameter-correctly/ >> > >> > >> > >> > Nicolas >> > >> > On 2020-11-27 12:08 a.m., Richard Duivenvoorde wrote: >> >> On 11/27/20 5:28 AM, Nicolas Cadieux wrote: >> >>> I want to learn to make a QGIS plugin and I was wondering if anybody >> >>> new if there is a QGIS plugin or tool that calculates the z factor >> >>> for a particular latitude? I thought this would be an easy project to >> >>> start with but I don't want to duplicate someone else's work. >> >> Hi Nicolas, >> >> >> >> What do you mean with "calculates the z factor for a particular >> >> latitude"? >> >> >> >> - z-factor as in x,y,z? >> >> - Do you mean based on a crs/datum? So more proj-based? >> >> - Or do you mean based on a known dataset with not enough z-info? So >> >> more extra/intrapolation? >> >> - Raster? Vector? >> >> - Creating a new dataset (processing)? Or just reporting for one lat >> >> (desktop/gui)? >> >> >> >> Just trying to get an idea of your idea :-) >> >> >> >> Regards, >> >> >> >> Richard Duivenvoorde >> >> >> >> >> >> >> ___ >> 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 > ___ > 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 ___ 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
Re: [Qgis-user] z factor
Hi, For now, probably just a box where you entre y and x and an select an ellipsoid. Ideally, you could just pick a raster and the latitude at the centre of the file and the project ellipsoid would be selected. I have the python formula for Proj as I use it in my python script. I just don’t normally use the QGIS API to program. Thanks for the input. Nicolas Cadieux https://gitlab.com/njacadieux > Le 27 nov. 2020 à 04:52, Raymond Nijssen a écrit : > > Hi Nicolas, > > It is just a simple formula for calculating the "z-factor" for a given > latitude. What would that look like in a plugin? Where would it go? What > would it do or show? > > Last week I had a similar idea for a plugin that could tell you which UTM > zone to pick for your current canvas. I decided it would not be worth the > effort. But maybe these could go together (and be finished at the end of this > "KwakFriday"? > > Regards, > Raymond > > >> On 27-11-2020 06:13, Nicolas Cadieux wrote: >> Hi, >> It's just the Z factor needed when you make a hillshade when the x an y are >> in degrees and the z is in feet or meters (like SRTM). You can see it if you >> choose Hillshade under symbology / render type (for a raster layer). It's >> basically the length of a degree in meters for latitude. >> https://www.esri.com/arcgis-blog/products/product/imagery/setting-the-z-factor-parameter-correctly/ >> Nicolas >>> On 2020-11-27 12:08 a.m., Richard Duivenvoorde wrote: >>> On 11/27/20 5:28 AM, Nicolas Cadieux wrote: I want to learn to make a QGIS plugin and I was wondering if anybody new if there is a QGIS plugin or tool that calculates the z factor for a particular latitude? I thought this would be an easy project to start with but I don't want to duplicate someone else's work. >>> Hi Nicolas, >>> >>> What do you mean with "calculates the z factor for a particular latitude"? >>> >>> - z-factor as in x,y,z? >>> - Do you mean based on a crs/datum? So more proj-based? >>> - Or do you mean based on a known dataset with not enough z-info? So more >>> extra/intrapolation? >>> - Raster? Vector? >>> - Creating a new dataset (processing)? Or just reporting for one lat >>> (desktop/gui)? >>> >>> Just trying to get an idea of your idea :-) >>> >>> Regards, >>> >>> Richard Duivenvoorde >>> >>> >>> > ___ > 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 ___ 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
Re: [Qgis-user] z factor
Hi, Thanks for the heads up. I will check. Nicolas Cadieux https://gitlab.com/njacadieux > Le 27 nov. 2020 à 06:01, Bernd Vogelgesang a écrit > : > > >> On 27.11.20 10:52, Raymond Nijssen wrote: >> ... >> Last week I had a similar idea for a plugin that could tell you which >> UTM zone to pick for your current canvas. I decided it would not be >> worth the effort. But maybe these could go together (and be finished >> at the end of this "KwakFriday"? > Isn't that already covered by the "Projestions" plugin? >> >> Regards, >> Raymond >> >> >>> On 27-11-2020 06:13, Nicolas Cadieux wrote: >>> Hi, >>> >>> It's just the Z factor needed when you make a hillshade when the x an >>> y are in degrees and the z is in feet or meters (like SRTM). You can >>> see it if you choose Hillshade under symbology / render type (for a >>> raster layer). It's basically the length of a degree in meters for >>> latitude. >>> >>> https://www.esri.com/arcgis-blog/products/product/imagery/setting-the-z-factor-parameter-correctly/ >>> >>> >>> Nicolas >>> >>> On 2020-11-27 12:08 a.m., Richard Duivenvoorde wrote: On 11/27/20 5:28 AM, Nicolas Cadieux wrote: > I want to learn to make a QGIS plugin and I was wondering if > anybody new if there is a QGIS plugin or tool that calculates the z > factor for a particular latitude? I thought this would be an easy > project to start with but I don't want to duplicate someone else's > work. Hi Nicolas, What do you mean with "calculates the z factor for a particular latitude"? - z-factor as in x,y,z? - Do you mean based on a crs/datum? So more proj-based? - Or do you mean based on a known dataset with not enough z-info? So more extra/intrapolation? - Raster? Vector? - Creating a new dataset (processing)? Or just reporting for one lat (desktop/gui)? Just trying to get an idea of your idea :-) Regards, Richard Duivenvoorde >> ___ >> 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 > ___ > 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 ___ 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
Re: [Qgis-user] z factor
I have a Lat Lon Tools plugin, Field Calculator function that generates the UTM zone. Nicolas, you just reminded me that you had suggested this to me earlier as a plugin. Something like that would be easy to add, but I'm not sure it fits within Lat Lon Tools which captures different coordinates, but z-factor is related to the latitude so perhaps it fits. Does anyone think it would be worth adding to Lat Lon Tools or should it be a separate plugin? Calvin On Fri, Nov 27, 2020 at 4:52 AM Raymond Nijssen wrote: > Hi Nicolas, > > It is just a simple formula for calculating the "z-factor" for a given > latitude. What would that look like in a plugin? Where would it go? What > would it do or show? > > Last week I had a similar idea for a plugin that could tell you which > UTM zone to pick for your current canvas. I decided it would not be > worth the effort. But maybe these could go together (and be finished at > the end of this "KwakFriday"? > > Regards, > Raymond > > > On 27-11-2020 06:13, Nicolas Cadieux wrote: > > Hi, > > > > It's just the Z factor needed when you make a hillshade when the x an y > > are in degrees and the z is in feet or meters (like SRTM). You can see > > it if you choose Hillshade under symbology / render type (for a raster > > layer). It's basically the length of a degree in meters for latitude. > > > > > https://www.esri.com/arcgis-blog/products/product/imagery/setting-the-z-factor-parameter-correctly/ > > > > > > Nicolas > > > > On 2020-11-27 12:08 a.m., Richard Duivenvoorde wrote: > >> On 11/27/20 5:28 AM, Nicolas Cadieux wrote: > >>> I want to learn to make a QGIS plugin and I was wondering if anybody > >>> new if there is a QGIS plugin or tool that calculates the z factor > >>> for a particular latitude? I thought this would be an easy project to > >>> start with but I don't want to duplicate someone else's work. > >> Hi Nicolas, > >> > >> What do you mean with "calculates the z factor for a particular > >> latitude"? > >> > >> - z-factor as in x,y,z? > >> - Do you mean based on a crs/datum? So more proj-based? > >> - Or do you mean based on a known dataset with not enough z-info? So > >> more extra/intrapolation? > >> - Raster? Vector? > >> - Creating a new dataset (processing)? Or just reporting for one lat > >> (desktop/gui)? > >> > >> Just trying to get an idea of your idea :-) > >> > >> Regards, > >> > >> Richard Duivenvoorde > >> > >> > >> > ___ > 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 > ___ 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
Re: [Qgis-user] z factor
Isn't that already covered by the "Projestions" plugin? Yes, something like that! I didn't know it. It doesn't give me any utm zone though.. ___ 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
Re: [Qgis-user] z factor
On 27.11.20 10:52, Raymond Nijssen wrote: ... Last week I had a similar idea for a plugin that could tell you which UTM zone to pick for your current canvas. I decided it would not be worth the effort. But maybe these could go together (and be finished at the end of this "KwakFriday"? Isn't that already covered by the "Projestions" plugin? Regards, Raymond On 27-11-2020 06:13, Nicolas Cadieux wrote: Hi, It's just the Z factor needed when you make a hillshade when the x an y are in degrees and the z is in feet or meters (like SRTM). You can see it if you choose Hillshade under symbology / render type (for a raster layer). It's basically the length of a degree in meters for latitude. https://www.esri.com/arcgis-blog/products/product/imagery/setting-the-z-factor-parameter-correctly/ Nicolas On 2020-11-27 12:08 a.m., Richard Duivenvoorde wrote: On 11/27/20 5:28 AM, Nicolas Cadieux wrote: I want to learn to make a QGIS plugin and I was wondering if anybody new if there is a QGIS plugin or tool that calculates the z factor for a particular latitude? I thought this would be an easy project to start with but I don't want to duplicate someone else's work. Hi Nicolas, What do you mean with "calculates the z factor for a particular latitude"? - z-factor as in x,y,z? - Do you mean based on a crs/datum? So more proj-based? - Or do you mean based on a known dataset with not enough z-info? So more extra/intrapolation? - Raster? Vector? - Creating a new dataset (processing)? Or just reporting for one lat (desktop/gui)? Just trying to get an idea of your idea :-) Regards, Richard Duivenvoorde ___ 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 ___ 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
Re: [Qgis-user] z factor
Hi Nicolas, It is just a simple formula for calculating the "z-factor" for a given latitude. What would that look like in a plugin? Where would it go? What would it do or show? Last week I had a similar idea for a plugin that could tell you which UTM zone to pick for your current canvas. I decided it would not be worth the effort. But maybe these could go together (and be finished at the end of this "KwakFriday"? Regards, Raymond On 27-11-2020 06:13, Nicolas Cadieux wrote: Hi, It's just the Z factor needed when you make a hillshade when the x an y are in degrees and the z is in feet or meters (like SRTM). You can see it if you choose Hillshade under symbology / render type (for a raster layer). It's basically the length of a degree in meters for latitude. https://www.esri.com/arcgis-blog/products/product/imagery/setting-the-z-factor-parameter-correctly/ Nicolas On 2020-11-27 12:08 a.m., Richard Duivenvoorde wrote: On 11/27/20 5:28 AM, Nicolas Cadieux wrote: I want to learn to make a QGIS plugin and I was wondering if anybody new if there is a QGIS plugin or tool that calculates the z factor for a particular latitude? I thought this would be an easy project to start with but I don't want to duplicate someone else's work. Hi Nicolas, What do you mean with "calculates the z factor for a particular latitude"? - z-factor as in x,y,z? - Do you mean based on a crs/datum? So more proj-based? - Or do you mean based on a known dataset with not enough z-info? So more extra/intrapolation? - Raster? Vector? - Creating a new dataset (processing)? Or just reporting for one lat (desktop/gui)? Just trying to get an idea of your idea :-) Regards, Richard Duivenvoorde ___ 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
Re: [Qgis-user] z factor
Nicolas, that would be helpful indeed! Yet I do it manually each time... Maria > Am 27.11.2020 um 14:13 schrieb Nicolas Cadieux : > > Hi, > > It's just the Z factor needed when you make a hillshade when the x an y are > in degrees and the z is in feet or meters (like SRTM). You can see it if you > choose Hillshade under symbology / render type (for a raster layer). It's > basically the length of a degree in meters for latitude. > > https://www.esri.com/arcgis-blog/products/product/imagery/setting-the-z-factor-parameter-correctly/ > > Nicolas > > On 2020-11-27 12:08 a.m., Richard Duivenvoorde wrote: >> On 11/27/20 5:28 AM, Nicolas Cadieux wrote: >>> I want to learn to make a QGIS plugin and I was wondering if anybody new if >>> there is a QGIS plugin or tool that calculates the z factor for a >>> particular latitude? I thought this would be an easy project to start with >>> but I don't want to duplicate someone else's work. >> Hi Nicolas, >> >> What do you mean with "calculates the z factor for a particular latitude"? >> >> - z-factor as in x,y,z? >> - Do you mean based on a crs/datum? So more proj-based? >> - Or do you mean based on a known dataset with not enough z-info? So more >> extra/intrapolation? >> - Raster? Vector? >> - Creating a new dataset (processing)? Or just reporting for one lat >> (desktop/gui)? >> >> Just trying to get an idea of your idea :-) >> >> Regards, >> >> Richard Duivenvoorde >> >> >> > -- > Nicolas Cadieux > https://gitlab.com/njacadieux > > ___ > 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 ___ 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
Re: [Qgis-user] z factor
Hi, It's just the Z factor needed when you make a hillshade when the x an y are in degrees and the z is in feet or meters (like SRTM). You can see it if you choose Hillshade under symbology / render type (for a raster layer). It's basically the length of a degree in meters for latitude. https://www.esri.com/arcgis-blog/products/product/imagery/setting-the-z-factor-parameter-correctly/ Nicolas On 2020-11-27 12:08 a.m., Richard Duivenvoorde wrote: On 11/27/20 5:28 AM, Nicolas Cadieux wrote: I want to learn to make a QGIS plugin and I was wondering if anybody new if there is a QGIS plugin or tool that calculates the z factor for a particular latitude? I thought this would be an easy project to start with but I don't want to duplicate someone else's work. Hi Nicolas, What do you mean with "calculates the z factor for a particular latitude"? - z-factor as in x,y,z? - Do you mean based on a crs/datum? So more proj-based? - Or do you mean based on a known dataset with not enough z-info? So more extra/intrapolation? - Raster? Vector? - Creating a new dataset (processing)? Or just reporting for one lat (desktop/gui)? Just trying to get an idea of your idea :-) Regards, Richard Duivenvoorde -- Nicolas Cadieux https://gitlab.com/njacadieux ___ 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
Re: [Qgis-user] z factor
On 11/27/20 5:28 AM, Nicolas Cadieux wrote: > I want to learn to make a QGIS plugin and I was wondering if anybody new if > there is a QGIS plugin or tool that calculates the z factor for a particular > latitude? I thought this would be an easy project to start with but I don't > want to duplicate someone else's work. Hi Nicolas, What do you mean with "calculates the z factor for a particular latitude"? - z-factor as in x,y,z? - Do you mean based on a crs/datum? So more proj-based? - Or do you mean based on a known dataset with not enough z-info? So more extra/intrapolation? - Raster? Vector? - Creating a new dataset (processing)? Or just reporting for one lat (desktop/gui)? Just trying to get an idea of your idea :-) Regards, Richard Duivenvoorde ___ 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
[Qgis-user] z factor
Hi, I want to learn to make a QGIS plugin and I was wondering if anybody new if there is a QGIS plugin or tool that calculates the z factor for a particular latitude? I thought this would be an easy project to start with but I don't want to duplicate someone else's work. Thanks for your comments. -- Nicolas Cadieux https://gitlab.com/njacadieux ___ 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
Re: [Qgis-user] z factor in aspect calculation?
I'd agree, the aspect of a slope does not vary with it's gradient, and the scale factor is only used to ensure that the gradient calculations are made using consistent units in XY & Z. Cheers, Andy On 11/10/2018 19:43, Nicolas Cadieux wrote: Hi, I use a z factor in slope and hill shade calculation when my DEMs are in Long/Lat and the altitudes in metres (like SRTM, ASTER GDEM...). In GdalDem , there is not a z factor or a scale option for Aspect (0-360D azimuth) but in the Qgis terrain analysis, there is. (It does not appear to work in Qgis 2.18.24). In Qgis 3.2.3, when using the QGIS Terrain analysis Aspect algorithm with a z factor of 1, I get identical results as in gdaldem and results look and feel good. I figure it's probably the same algorithm running in the background. What more, the aspect file is similar to result done on a reprojected DEM in a local UTM zone (where no z factor is needed as everything is in metres). Reprojecting is not an option for my project. In the QGIS Terrain analysis Aspect algorithm, if I use 0.126 as the correct z factor for the area (1 / The length of a Degree of Longitude in metres at a latitude of 45N) (or 1/78847=0.126) my results are very wrong. I wonder if using a z factor (0.126) is not needed for the aspect calculation and that this should be removed from the QGIS Terrain Analysis aspect options. Any thoughts? Nicolas ___ 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 -- Andy Harfoot GeoData Institute University of Southampton Southampton SO17 1BJ Tel: +44 (0)23 8059 2719 www.geodata.soton.ac.uk ___ 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
[Qgis-user] z factor in aspect calculation?
Hi, I use a z factor in slope and hill shade calculation when my DEMs are in Long/Lat and the altitudes in metres (like SRTM, ASTER GDEM...). In GdalDem , there is not a z factor or a scale option for Aspect (0-360D azimuth) but in the Qgis terrain analysis, there is. (It does not appear to work in Qgis 2.18.24). In Qgis 3.2.3, when using the QGIS Terrain analysis Aspect algorithm with a z factor of 1, I get identical results as in gdaldem and results look and feel good. I figure it's probably the same algorithm running in the background. What more, the aspect file is similar to result done on a reprojected DEM in a local UTM zone (where no z factor is needed as everything is in metres). Reprojecting is not an option for my project. In the QGIS Terrain analysis Aspect algorithm, if I use 0.126 as the correct z factor for the area (1 / The length of a Degree of Longitude in metres at a latitude of 45N) (or 1/78847=0.126) my results are very wrong. I wonder if using a z factor (0.126) is not needed for the aspect calculation and that this should be removed from the QGIS Terrain Analysis aspect options. Any thoughts? Nicolas ___ 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
