[Qgis-user] z factor

[Nicolas Cadieux]

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 <r.nijssen at terglobo.nl> 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
>>> 
>>> 
>>> 
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