[Qgis-user] vector point grid to raster grid -- pixel size does not work

[Priv.-Doz. Dr. Maria Shinoto]

Chris, 

Thanks for helping me out. Your detailed explanation was really helpful. I could not have done without it, thanks for taking so much time. 

A short memo about what I did is in my answer to Nicolas Cadieux. 

Best, 
Maria


> Am 13.05.2020 um 01:36 schrieb chris hermansen <clhermansen at gmail.com>:
> 
> Maria and list,
> 
> On Tue, May 12, 2020 at 4:24 AM Priv.-Doz. Dr. Maria Shinoto <maria.shinoto at zaw.uni-heidelberg.de> wrote:
> Hi, 
> 
> I am having problems to set up the parameters for Raster > Convert > Rasterize Vector to Raster
> 
> My basic map is JGD2011 / Japan Plnae Rectangular CS II, and I downloaded an xml file JPGIS/GML format, that had to be converted to shapefile in a special application. 
> 
> So according to this https://epsg.io/30162 that projection is:
> Coordinate system: Cartesian 2D CS. Axes: northing, easting (X,Y). Orientations: north, east. UoM: m.
> 
> 
> 
> 
> Now I have the points as a grid with approximately 5m distance and want to convert them to Raster, since this is what I want to use as DEM for analyses. 
> 
> Everything works, but the pixel are extremely largen, not 5m.
> 
> I set the units to pixel, and since it is 5m mesh (from 0.2 seconds), I was told to use 0.000056 for horizontal and vertical resolution, but I do not know what I am doing there, and I do not find any similar application in tutorials, handbooks and books, the options in QGIS documentation do not really help. 
> 
> This sounds completely incorrect to me.  I believe you should specifically set the following on your Rasterize (Vector to Raster) dialogue:
> 
> Output raster size units: Georeferenced units
> 
> Width/Horizontal resolution: 5.0
> 
> Height/Vertical resolution: 5.0
> 
> Output extent -> use canvas extent
> 
> 
> Can anybody guide me to the correct value? Or to another flaw in my thinking?
> 
> 
> Since your input point data is in a cartesian (ie x-y) projection and in metres (apparently with Tokyo as its zero point), and since you want your output raster in metres in the same reference system, there is no need to be thinking about how many seconds correspond to metres at your latitude, nor pixels, nor anything like that.
> 
> If you refer to the link above describing the Japan Plane Regular CS II projection, you will see it is based on the Bessel 1841 spheroid.  It may be useful for you to set your project properties before doing the vector to raster conversion.
> 
> Select Project > Properties > CRS, then use the filter to find Tokyo / Japan Plane Rectangular CS II EPSG:30162  Select that coordinate reference system and click Apply.  The menu should look like this:
> 
> <Screenshot from 2020-05-12 09-33-29.png>
> 
> 
> -- 
> Chris Hermansen · clhermansen "at" gmail "dot" com
> 
> C'est ma façon de parler.