I've not been able to actually get EGM96 to WGS84 transformations to work in PROJ C++. I have however, gotten what I want to work in python, via pyproj, like this:
from pyproj import Transformer, CRS
from pyproj.transformer import TransformerGroup, TransformDirection
from pyproj.datadir import append_data_dir, get_data_dir
def main():
lat = 43.70012234
lng = -79.41629234
z = 100
append_data_dir("/absolute_directory_to/proj/")
transformer = Transformer.from_crs("epsg:4326", "epsg:5773",)
results = transformer.transform(lat, lng, z, None, False, True, TransformDirection.INVERSE)
print(results)
if __name__ == "__main__":
main()
This provides the result:
(43.70012234, -79.41629234, 62.71016021909354)
And the file us_nga_egm96_15.tif located in the ./proj/ directory
However, my replication of the same in C++ doesn't appear to work.
#include <proj.h>
#include <filesystem>
#include <array>
void main(){
auto proj_context = proj_context_create();
const char * path = "/absolute_directory_to/proj";
const char * db_path = proj_context_get_database_path(proj_context);
std::filesystem::path db_path_path = std::filesystem::path(db_path);
std::string db_path_str = db_path_path.parent_path().string();
std::array paths = {path, db_path_str.c_str()};
proj_context_set_search_paths(proj_context, paths.size(), paths.data());
std::cout << proj_errno_string(proj_context_errno(proj_context)) << std::endl;
auto temp = proj_create_crs_to_crs (proj_context,
"EPSG:4326",
"EPSG:5773",
NULL);
std::cout << proj_errno_string(proj_errno(temp)) << std::endl;
std::cout << proj_errno_string(proj_context_errno(proj_context)) << std::endl;
auto b = proj_trans(temp, PJ_INV, {43.70012234,-79.41629234,100,0});
std::cout << proj_errno_string(proj_errno(temp)) << std::endl;
std::cout << proj_errno_string(proj_context_errno(proj_context)) << std::endl;
std::cout << b.v[0] << "," << b.v[1] << "," << b.v[2] << "," << b.v[3] << std::endl;
std::cout << proj_errno_string(proj_errno(temp)) << std::endl;
std::cout << proj_errno_string(proj_context_errno(proj_context)) << std::endl;
proj_destroy(temp);
proj_context_destroy(proj_context);
return 0;
}
It actually prints out nothing (some strange character seems to be eating all the other characters), and in debug mode, I can see that b = {inf,inf,inf,inf}. Same thing happens if I don't manually specify the proj locaiton (but make sure the actual .tiff is located there).
What am I doing wrong here?
