walker ( Walker )

  // Explicitly skip datum transform by setting 'datum=none' as parameter for either source or dest
  if (source.datum_type === PJD_NODATUM && dest.datum_type !== PJD_GRIDSHIFT || dest.datum_type === PJD_NODATUM && screen.datum_type !== PJD_GRIDSHIFT) {
    return point;
  }

th30d0r

comment created time in 3 hours

issue commentproj4js/proj4js

Proj4 js nadgrid transform does not take into account the nadgrid param

Yep I just tested this. If i provide the from proj4 string of 27700 the transform works perfectly. However It cannot convert points from 3857

th30d0r

comment created time in 3 hours

issue commentproj4js/proj4js

Proj4 js nadgrid transform does not take into account the nadgrid param

Even with the @ it does not work. The transform is done after the key is registered. I think i tracked it down to this area of the code in the datum_transform.js - which is where i assume the gridshift is happening.

export default function(source, dest, point) {
  // Short cut if the datums are identical.
  if (compareDatums(source, dest)) {
    return point; // in this case, zero is sucess,
    // whereas cs_compare_datums returns 1 to indicate TRUE
    // confusing, should fix this
  }

  // Explicitly skip datum transform by setting 'datum=none' as parameter for either source or dest
  if (source.datum_type === PJD_NODATUM || dest.datum_type === PJD_NODATUM) {
    return point;
  }

  // If this datum requires grid shifts, then apply it to geodetic coordinates.
  var source_a = source.a;
  var source_es = source.es;
  if (source.datum_type === PJD_GRIDSHIFT) {
    var gridShiftCode = applyGridShift(source, false, point);
    if (gridShiftCode !== 0) {
      return undefined;
    }
    source_a = SRS_WGS84_SEMIMAJOR;
    source_es = SRS_WGS84_ESQUARED;
  }

  var dest_a = dest.a;
  var dest_b = dest.b;
  var dest_es = dest.es;
  if (dest.datum_type === PJD_GRIDSHIFT) {
    dest_a = SRS_WGS84_SEMIMAJOR;
    dest_b = SRS_WGS84_SEMIMINOR;
    dest_es = SRS_WGS84_ESQUARED;
  }

The applyGridShift(source, false, point) function is not called because it exits the function here // Explicitly skip datum transform by setting 'datum=none' as parameter for either source or dest if (source.datum_type === PJD_NODATUM || dest.datum_type === PJD_NODATUM) { return point; }

th30d0r

comment created time in 4 hours

issue commentproj4js/proj4js

Proj4 js nadgrid transform does not take into account the nadgrid param

You need to prefix the grid key with a @. In your def, it should be +nadgrids=@key,null. Also make sure you don't perform the transform before the key is registered - you're setting it asynchronously.

th30d0r

comment created time in 4 hours

issue commentproj4js/proj4js

nadgrid not a type of @types/proj4

Thanks

th30d0r

comment created time in 4 hours

issue openedproj4js/proj4js

Proj4 js nadgrid transform does not take into account the nadgrid param

When using the js binding for proj4 with nadgrid param, the output coordinate transform is the same as without the nadgrid param in the proj4 string

the proj4 string customProj4 = +proj=tmerc +lat_0=52.3 +lon_0=-1.5 +k=1 +x_0=198873.0046 +y_0=375064.3871 +ellps=WGS84 +units=m +no_defs +nadgrids=key
Reading the gsb file into a buffer array switchMap(gsbFileResp => { const buffer = gsbFileResp.arrayBuffer(); return from(buffer); }) ) .subscribe(buffer => { (proj4 as any).nadgrid('key', buffer); }

transform code proj4For3857 = '+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs',

proj4(proj4For3857,customProj4, coordinate)

The output transformed coordinate has a shift, and it is the same out as if I remove the nadgrid param from the custom proj4 string

Using Angular 10 proj4 2.7.4

created time in 4 hours

issue commentproj4js/proj4js

nadgrid not a type of @types/proj4

Please submit a pull request or an issue to https://github.com/DefinitelyTyped/DefinitelyTyped.

th30d0r

comment created time in 5 hours

issue openedproj4js/proj4js

nadgrid not a type of @types/proj4

code: proj4.nadgrid('key', buffer);