Wrong projection between WGS84 and GDM2000/Peninsular RSO

[sergemarkin]

The issue #173 which was closed is still there.

My code:

var epsg4326 = '+proj=longlat +datum=WGS84 +no_defs'

var epsg3375 = '+proj=omerc +lat_0=4 +lonc=102.25 +alpha=323.0257964666666 +k=0.99984 +x_0=804671 +y_0=0 +no_uoff +gamma=323.1301023611111 +ellps=GRS80 +units=m +no_defs'

var transformation = proj4(epsg4326, epsg3375)
var input = [101.70979078430528, 3.06268465621428];
var output = transformation.forward(input);
// 744626.6428051005, -103618.62269607143
// expected: 412597.532715, 338944.957259

I tried previous versions and got the same wrong results.

JSFiddle

[ceylanb]

+1

[shanmugamg]

+1
faced with the similar problem and yet to find a solution

[calvinmetcalf]

ok my first thought is that we aren't doing anything with the field gamma/rectified_grid_angle, but esri wkt files don't include that one so that's probably not it, looking at our tests we do have one for another omerc, but it's azimuth is only 90, I tested alaska state plane zone 1 and found that also doesn't work right, I suspect there has always been a bug in omerc, will look into it more

[Ariki]

As far as I understand, Proj4js seems to ignore +gamma parameter, whereas proj C library allows to specify it (by default it's assumed to be equal to +alpha). So projections that have gamma != alpha do not work correctly.

[thedmi]

I've opened an issue for the difference in behavior between proj4 and proj4js, see #301