Merge pull request #2000 from brownag/proj-fixes1

fix: PROJ initialization and network behavior

Author: rhijmans

NAMESPACE

@@ -21,6 +21,6 @@ S3method(str, SpatRaster)
 S3method(str, SpatExtent)
 S3method(str, SpatGraticule)
 
-export(add_abline, add_box, add_legend, add_grid, add_mtext, ar_info, clearVSIcache, combineLevels, focalMat, extractAlong, gdal, getGDALconfig, graticule, halo, libVersion, proj_ok, setGDALconfig, map.pal, map_extent, north, sbar, terraOptions, tmpFiles, makeVRT, mem_info, free_RAM, same.crs, shade, gdalCache, fileBlocksize, vector_layers, vrt_tiles, names, round, unloadGDALdrivers)
+export(add_abline, add_box, add_legend, add_grid, add_mtext, ar_info, clearVSIcache, combineLevels, focalMat, extractAlong, gdal, getGDALconfig, graticule, halo, libVersion, proj_ok, projNetwork, projPaths, setGDALconfig, map.pal, map_extent, north, sbar, terraOptions, tmpFiles, makeVRT, mem_info, free_RAM, same.crs, shade, gdalCache, fileBlocksize, vector_layers, vrt_tiles, names, round, unloadGDALdrivers)
 
 

R/RcppExports.R

@@ -113,8 +113,8 @@ rgb2hex <- function(x) {
     .Call(`_terra_get_proj_search_paths`)
 }
 
-.set_proj_search_paths <- function(paths) {
-    .Call(`_terra_set_proj_search_paths`, paths)
+.set_proj_search_paths <- function(paths, with_proj = FALSE) {
+    .Call(`_terra_set_proj_search_paths`, paths, with_proj)
 }
 
 .PROJ_network <- function(enable, url) {

R/gdal.R

@@ -9,6 +9,37 @@ proj_ok <- function() {
 }
 
 
+projNetwork <- function(enable, url="") {
+	if (missing(enable)) {
+		as.logical(.PROJ_network(-1, ""))
+	} else {
+		if (enable) {
+			out <- .PROJ_network(1, url)
+			if (out != "") {
+				message("PROJ network enabled. Using CDN URL: ", out)
+			} else {
+				message("PROJ network enabled")
+			}
+		} else {
+			.PROJ_network(0, "")
+			message("PROJ network disabled")
+		}
+		invisible(NULL)
+	}
+}
+
+
+projPaths <- function(paths, with_proj = TRUE) {
+	if (missing(paths)) {
+		.get_proj_search_paths()
+	} else {
+		paths <- as.character(paths)
+		.set_proj_search_paths(paths, with_proj)
+		invisible(.get_proj_search_paths())
+	}
+}
+
+
 fileBlocksize <- function(x) {
 	v <- x@pntr$getFileBlocksize()
 	m <- matrix(v, ncol=2)

R/zzz.R

@@ -24,16 +24,18 @@
 
 .gdinit <- function() {
 	path = ""
-	sf <- system.file("", package="terra")
-	if (file.exists(file.path(sf, "proj/nad.lst"))) {
-		path <- system.file("proj", package="terra")
-		.gdalinit(path, file.path(sf, "gdal"))
-		if ( Sys.info()["sysname"] == "Windows" ) {
-			.set_proj_search_paths(path)
-		}
-	} else {
-		.gdalinit(path, file.path(sf, "gdal"))
+	proj_path <- system.file("proj", package="terra")
+	gdal_path <- system.file("gdal", package="terra")
+	
+	has_proj <- dir.exists(proj_path) && (file.exists(file.path(proj_path, "proj.db")) || file.exists(file.path(proj_path, "nad.lst")))
+	has_gdal <- dir.exists(gdal_path)
+	
+	if (has_proj) {
+		projPaths(proj_path, TRUE)
 	}
+	
+	.gdalinit(path, ifelse(has_gdal, gdal_path, ""))
+	
 	if (libVersion("gdal") == "3.6.0") {
 		message("Using GDAL version 3.6.0 which was retracted because it cannot write large GPKG files")
 	}

man/gdal.Rd

@@ -8,9 +8,11 @@
 \alias{setGDALconfig}
 \alias{unloadGDALdrivers}
 \alias{proj_ok}
+\alias{projNetwork}
+\alias{projPaths}
 
 
-\title{GDAL version, supported file formats, and cache size}
+\title{GDAL version, supported file formats, cache size, and PROJ coordinate transformation control}
 
 \description{
 Set the \code{GDAL} warning level or get a \code{data.frame} with the available GDAL drivers (file formats), or, if \code{warn=NA} and \code{drivers=FALSE}, you get the version numbers of one or all of the GDAL, PROJ and GEOS libraries. 
@@ -20,6 +22,10 @@ Set the \code{GDAL} warning level or get a \code{data.frame} with the available
 The current \code{GDAL} configuration options and obtained with \code{getGDALconfig} and changed with \code{setGDALconfig}. 
 
 \code{proj_ok} checks if the PROJ database with CRS definitions can be found.
+
+\code{projNetwork} controls whether PROJ can access network resources for coordinate transformations. By default, network access is enabled to provide high-accuracy grid-based datum transformations where available. When disabled, PROJ falls back to \href{https://proj.org/en/stable/glossary.html#term-Ballpark-transformation}{"ballpark transformations"} (of unknown accuracy) which could lead to errors of hundreds of meters in some cases. When enabled, PROJ downloads transformation grids from \code{https://cdn.proj.org}, requiring network connectivity and valid SSL certificates. After a successful run, the files are cached locally.
+
+\code{projPaths} gets or sets the search paths that PROJ uses to find coordinate system definitions and transformation grids. This allows users to specify custom locations for PROJ data files, such as when using offline installations or custom grid files. By default, it operates on PROJ search paths, but can also set GDAL search paths when \code{with_proj=FALSE}.
 }
 
 \usage{
@@ -31,6 +37,8 @@ clearVSIcache()
 libVersion(lib="all", parse=FALSE)
 unloadGDALdrivers(x)
 proj_ok()
+projNetwork(enable, url="")
+projPaths(paths, with_proj = TRUE)
 }
 
 \arguments{
@@ -42,21 +50,32 @@ proj_ok()
   \item{value}{character. value for GDAL configuration option. Use "" to reset it to its default value}
   \item{lib}{character. "gdal", "proj", or "geos", or any other value to get the versions numbers of all three}
   \item{parse}{logical. Should the version be parsed into three numerical values (major, minor and sub versions)?}
-  \item{x}{character. Drivers names such as "GTiff" to be unloaded. Or "" to reload all drivers}  
+  \item{x}{character. Drivers names such as "GTiff" to be unloaded. Or "" to reload all drivers}
+  \item{enable}{logical. If \code{TRUE}, enable PROJ network access for high-accuracy grid-based transformations. If \code{FALSE}, disable network access and use ballpark transformations. If missing, return the current network status}
+  \item{url}{character. Optional URL for PROJ network endpoint. If empty string (default), uses PROJ's default network settings (\code{https://cdn.proj.org})}
+  \item{paths}{character. Vector of file paths to directories containing PROJ data files. If missing, returns the current search paths}
+  \item{with_proj}{logical. If \code{TRUE} (default), set PROJ search paths. If \code{FALSE}, set GDAL search paths}
 }
 
 
 \seealso{\code{\link{describe}} for file-level metadata "GDALinfo"}
 
 \value{
-character
+character vector of search paths. When setting paths, the result is returned invisibly.
 }
 
 \examples{
 gdal()
 gdal(2)
 head(gdal(drivers=TRUE))
 libVersion("all", TRUE)
+projNetwork()
+projPaths()
+projPaths(c("/custom/proj/path"))
+}
+
+\note{
+While some spatial analyses may not be greatly affected by PROJ network settings (ballpark vs. grid-based transformations), the differences can be significant, especially when a transformation involves a shift in datum between different coordinate reference systems. For applications requiring high positional accuracy, ensure network access is enabled or grids are locally available. Grids can be pre-downloaded using the \code{projsync} utility or installed via system packages, such as \code{proj-data} on Ubuntu/Debian systems. Downloaded grids are cached locally and then reused for subsequent transformations. 
 }
 
 \keyword{spatial}

src/RcppExports.cpp

@@ -319,23 +319,24 @@ BEGIN_RCPP
 END_RCPP
 }
 // set_proj_search_paths
-bool set_proj_search_paths(std::vector<std::string> paths);
-RcppExport SEXP _terra_set_proj_search_paths(SEXP pathsSEXP) {
+bool set_proj_search_paths(std::vector<std::string> paths, bool with_proj);
+RcppExport SEXP _terra_set_proj_search_paths(SEXP pathsSEXP, SEXP with_projSEXP) {
 BEGIN_RCPP
     Rcpp::RObject rcpp_result_gen;
     Rcpp::RNGScope rcpp_rngScope_gen;
     Rcpp::traits::input_parameter< std::vector<std::string> >::type paths(pathsSEXP);
-    rcpp_result_gen = Rcpp::wrap(set_proj_search_paths(paths));
+    Rcpp::traits::input_parameter< bool >::type with_proj(with_projSEXP);
+    rcpp_result_gen = Rcpp::wrap(set_proj_search_paths(paths, with_proj));
     return rcpp_result_gen;
 END_RCPP
 }
 // PROJ_network
-std::string PROJ_network(bool enable, std::string url);
+std::string PROJ_network(int enable, std::string url);
 RcppExport SEXP _terra_PROJ_network(SEXP enableSEXP, SEXP urlSEXP) {
 BEGIN_RCPP
     Rcpp::RObject rcpp_result_gen;
     Rcpp::RNGScope rcpp_rngScope_gen;
-    Rcpp::traits::input_parameter< bool >::type enable(enableSEXP);
+    Rcpp::traits::input_parameter< int >::type enable(enableSEXP);
     Rcpp::traits::input_parameter< std::string >::type url(urlSEXP);
     rcpp_result_gen = Rcpp::wrap(PROJ_network(enable, url));
     return rcpp_result_gen;
@@ -480,7 +481,7 @@ static const R_CallMethodDef CallEntries[] = {
     {"_terra_setGDALCacheSizeMB", (DL_FUNC) &_terra_setGDALCacheSizeMB, 2},
     {"_terra_getGDALCacheSizeMB", (DL_FUNC) &_terra_getGDALCacheSizeMB, 1},
     {"_terra_get_proj_search_paths", (DL_FUNC) &_terra_get_proj_search_paths, 0},
-    {"_terra_set_proj_search_paths", (DL_FUNC) &_terra_set_proj_search_paths, 1},
+    {"_terra_set_proj_search_paths", (DL_FUNC) &_terra_set_proj_search_paths, 2},
     {"_terra_PROJ_network", (DL_FUNC) &_terra_PROJ_network, 2},
     {"_terra_removeDriver", (DL_FUNC) &_terra_removeDriver, 1},
     {"_terra_pearson_cor", (DL_FUNC) &_terra_pearson_cor, 3},

src/RcppFunctions.cpp

@@ -434,14 +434,14 @@ void gdal_init(std::string projpath, std::string datapath) {
 	//GDAL_NETCDF_IGNORE_XY_AXIS_NAME_CHECKS
 
 	//GDALregistred = true;
-#if GDAL_VERSION_MAJOR >= 3
- #ifdef PROJ_6
 	if (!projpath.empty()) {
-		const char *cp = projpath.c_str();
-		proj_context_set_search_paths(PJ_DEFAULT_CTX, 1, &cp);
-	}
- #endif
+#if GDAL_VERSION_NUM >= 3000000
+		std::vector<char *> cpaths(2);
+		cpaths[0] = (char *)projpath.c_str();
+		cpaths[1] = NULL;
+		OSRSetPROJSearchPaths(cpaths.data());
 #endif
+	}
 #ifdef PROJ_71
 	#ifndef __EMSCRIPTEN__
 		proj_context_set_enable_network(PJ_DEFAULT_CTX, 1);
@@ -567,36 +567,54 @@ std::vector<std::string> get_proj_search_paths() {
 
 
 // [[Rcpp::export(name = ".set_proj_search_paths")]]
-bool set_proj_search_paths(std::vector<std::string> paths) {
+bool set_proj_search_paths(std::vector<std::string> paths, bool with_proj = false) {
 	if (paths.empty()) {
 		return false;
 	}
+	if (with_proj) {
+		// Set for PROJ library
+		if (paths.size() == 1) {
+			const char *cp = paths[0].c_str();
+			proj_context_set_search_paths(PJ_DEFAULT_CTX, 1, &cp);
+		}
+		return true;
+	} else {
+		// Set for GDAL
 #if GDAL_VERSION_NUM >= 3000000
-	std::vector <char *> cpaths(paths.size()+1);
-	for (size_t i = 0; i < paths.size(); i++) {
-		cpaths[i] = (char *) (paths[i].c_str());
-	}
-	cpaths[cpaths.size()-1] = NULL;
-	OSRSetPROJSearchPaths(cpaths.data());
-	return true;
+		std::vector <char *> cpaths(paths.size()+1);
+		for (size_t i = 0; i < paths.size(); i++) {
+			cpaths[i] = (char *) (paths[i].c_str());
+		}
+		cpaths[cpaths.size()-1] = NULL;
+		OSRSetPROJSearchPaths(cpaths.data());
+		return true;
 #else
-	return false;
+		return false;
 #endif
+	}
 }
 
 
 // [[Rcpp::export(name = ".PROJ_network")]]
-std::string PROJ_network(bool enable, std::string url) {
+std::string PROJ_network(int enable, std::string url) {
 	std::string s = "";
 #ifdef PROJ_71
-	if (enable) {
+	if (enable == -1) { // get current status
+		return std::to_string(proj_context_is_network_enabled(PJ_DEFAULT_CTX));
+	} else if (enable == 1) {
 		proj_context_set_enable_network(PJ_DEFAULT_CTX, 1);
+#if GDAL_VERSION_NUM >= 3040000
+		OSRSetPROJEnableNetwork(1);
+#endif
 		if (url.size() > 5) {
 			proj_context_set_url_endpoint(PJ_DEFAULT_CTX, url.c_str());
 		}
 		s = proj_context_get_url_endpoint(PJ_DEFAULT_CTX);
-	} else { // disable:
+	} else if (enable == 0) { // disable:
 		proj_context_set_enable_network(PJ_DEFAULT_CTX, 0);
+#if GDAL_VERSION_NUM >= 3040000
+		OSRSetPROJEnableNetwork(0);
+#endif
 	}
 #endif
 	return s;