Helmert: fix regression when rotation terms are 0, but scale is not (#2336)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

1 files changed, 2 insertions, 6 deletions

diff --git a/src/transformations/helmert.cpp b/src/transformations/helmert.cpp
index 9fb568a8..d3857d89 100644
--- a/src/transformations/helmert.cpp
+++ b/src/transformations/helmert.cpp
@@ -373,7 +373,7 @@ static PJ_XYZ helmert_forward_3d (PJ_LPZ lpz, PJ *P) {
         return point.xyz;
     }
 
-    if (Q->no_rotation) {
+    if (Q->no_rotation && Q->scale == 0) {
         point.xyz.x = lpz.lam + Q->xyz.x;
         point.xyz.y = lpz.phi + Q->xyz.y;
         point.xyz.z = lpz.z   + Q->xyz.z;
@@ -413,7 +413,7 @@ static PJ_LPZ helmert_reverse_3d (PJ_XYZ xyz, PJ *P) {
         return point.lpz;
     }
 
-    if (Q->no_rotation) {
+    if (Q->no_rotation && Q->scale == 0) {
         point.xyz.x  =  xyz.x - Q->xyz.x;
         point.xyz.y  =  xyz.y - Q->xyz.y;
         point.xyz.z  =  xyz.z - Q->xyz.z;
@@ -678,10 +678,6 @@ PJ *TRANSFORMATION(helmert, 0) {
         proj_log_trace(P, "ds= %8.5f  t_epoch=%8.5f", Q->dscale, Q->t_epoch);
     }
 
-    if (Q->no_rotation) {
-        return P;
-    }
-
     update_parameters(P);
     build_rot_matrix(P);