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Optimize +step +proj=helmert +inv +x=X +y=Y +z=Z +step +proj=helmert +inv +x=-X +y=-Y +z=-Z as +proj=noop #4775

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Merged
rouault merged 1 commit into from
May 11, 2026
+167 −25
Merged

Optimize +step +proj=helmert +inv +x=X +y=Y +z=Z +step +proj=helmert +inv +x=-X +y=-Y +z=-Z as +proj=noop #4775

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15 changes: 10 additions & 5 deletions src/iso19111/io.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9495,7 +9495,6 @@ const std::string &PROJStringFormatter::toString() const {
}

if (curStep.name == "helmert" && prevStep.name == "helmert" &&
!curStep.inverted && !prevStep.inverted &&
curStepParamCount == 3 &&
curStepParamCount == prevStepParamCount) {
std::map<std::string, double> leftParamsMap;
Expand All @@ -9520,12 +9519,18 @@ const std::string &PROJStringFormatter::toString() const {
rightParamsMap.find(y) != rightParamsMap.end() &&
rightParamsMap.find(z) != rightParamsMap.end()) {

const double xSum = leftParamsMap[x] + rightParamsMap[x];
const double ySum = leftParamsMap[y] + rightParamsMap[y];
const double zSum = leftParamsMap[z] + rightParamsMap[z];
const double signLeft = prevStep.inverted ? -1 : 1;
const double signRight = curStep.inverted ? -1 : 1;
const double xSum = signLeft * leftParamsMap[x] +
signRight * rightParamsMap[x];
const double ySum = signLeft * leftParamsMap[y] +
signRight * rightParamsMap[y];
const double zSum = signLeft * leftParamsMap[z] +
signRight * rightParamsMap[z];
if (xSum == 0.0 && ySum == 0.0 && zSum == 0.0) {
deletePrevAndCurIter();
} else {
prevStep.inverted = false;
prevStep.paramValues[0] =
Step::KeyValue("x", internal::toString(xSum));
prevStep.paramValues[1] =
Expand All @@ -9542,7 +9547,7 @@ const std::string &PROJStringFormatter::toString() const {

// Helmert followed by its inverse is a no-op
if (curStep.name == "helmert" && prevStep.name == "helmert" &&
!curStep.inverted && !prevStep.inverted &&
(curStep.inverted == prevStep.inverted) &&
curStepParamCount == prevStepParamCount) {
std::set<std::string> leftParamsSet;
std::set<std::string> rightParamsSet;
Expand Down
177 changes: 157 additions & 20 deletions test/unit/test_io.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -10201,31 +10201,137 @@ TEST(io, projstringformatter_helmert_7_param_noop) {
// ---------------------------------------------------------------------------

TEST(io, projstringformatter_merge_consecutive_helmert_3_param) {
auto fmt = PROJStringFormatter::create();
fmt->addStep("helmert");
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);
fmt->addStep("helmert");
fmt->addParam("x", -1);
fmt->addParam("y", -2);
fmt->addParam("z", -3);
EXPECT_EQ(fmt->toString(), "+proj=helmert +x=9 +y=18 +z=27");
{
auto fmt = PROJStringFormatter::create();
fmt->addStep("helmert");
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);

fmt->addStep("helmert");
fmt->addParam("x", -1);
fmt->addParam("y", -2);
fmt->addParam("z", -3);
EXPECT_EQ(fmt->toString(), "+proj=helmert +x=9 +y=18 +z=27");
}

{
auto fmt = PROJStringFormatter::create();
fmt->addStep("helmert");
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);

fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", -10);
fmt->addParam("y", -20);
fmt->addParam("z", -30);
EXPECT_EQ(fmt->toString(), "+proj=helmert +x=20 +y=40 +z=60");
}

{
auto fmt = PROJStringFormatter::create();
fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);

fmt->addStep("helmert");
fmt->addParam("x", -10);
fmt->addParam("y", -20);
fmt->addParam("z", -30);
EXPECT_EQ(fmt->toString(), "+proj=helmert +x=-20 +y=-40 +z=-60");
}
}

// ---------------------------------------------------------------------------

TEST(io, projstringformatter_merge_consecutive_helmert_3_param_noop) {
auto fmt = PROJStringFormatter::create();
fmt->addStep("helmert");
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);
fmt->addStep("helmert");
fmt->addParam("x", -10);
fmt->addParam("y", -20);
fmt->addParam("z", -30);
EXPECT_EQ(fmt->toString(), "+proj=noop");
{
auto fmt = PROJStringFormatter::create();
fmt->addStep("helmert");
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);

fmt->addStep("helmert");
fmt->addParam("x", -10);
fmt->addParam("y", -20);
fmt->addParam("z", -30);
EXPECT_EQ(fmt->toString(), "+proj=noop");
}

{
auto fmt = PROJStringFormatter::create();
fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);

fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", -10);
fmt->addParam("y", -20);
fmt->addParam("z", -30);
EXPECT_EQ(fmt->toString(), "+proj=noop");
}
}

// ---------------------------------------------------------------------------

TEST(io, projstringformatter_merge_consecutive_helmert_7_param_noop) {
{
auto fmt = PROJStringFormatter::create();
fmt->addStep("helmert");
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);
fmt->addParam("rx", 1);
fmt->addParam("ry", 2);
fmt->addParam("rz", 3);
fmt->addParam("s", 4);
fmt->addParam("convention", "position_vector");

fmt->addStep("helmert");
fmt->addParam("x", -10);
fmt->addParam("y", -20);
fmt->addParam("z", -30);
fmt->addParam("rx", -1);
fmt->addParam("ry", -2);
fmt->addParam("rz", -3);
fmt->addParam("s", -4);
fmt->addParam("convention", "position_vector");
EXPECT_EQ(fmt->toString(), "+proj=noop");
}

{
auto fmt = PROJStringFormatter::create();
fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);
fmt->addParam("rx", 1);
fmt->addParam("ry", 2);
fmt->addParam("rz", 3);
fmt->addParam("s", 4);
fmt->addParam("convention", "position_vector");

fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", -10);
fmt->addParam("y", -20);
fmt->addParam("z", -30);
fmt->addParam("rx", -1);
fmt->addParam("ry", -2);
fmt->addParam("rz", -3);
fmt->addParam("s", -4);
fmt->addParam("convention", "position_vector");
EXPECT_EQ(fmt->toString(), "+proj=noop");
}
}

// ---------------------------------------------------------------------------
Expand All @@ -10242,11 +10348,37 @@ TEST(io, projstringformatter_merge_inverted_helmert_with_opposite_conventions) {
fmt->addParam("rz", 3);
fmt->addParam("s", 4);
fmt->addParam("convention", "position_vector");

fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);
fmt->addParam("rx", -1);
fmt->addParam("ry", -2);
fmt->addParam("rz", -3);
fmt->addParam("s", 4);
fmt->addParam("convention", "coordinate_frame");
EXPECT_EQ(fmt->toString(), "+proj=noop");
}

{
auto fmt = PROJStringFormatter::create();
fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);
fmt->addParam("rx", 1);
fmt->addParam("ry", 2);
fmt->addParam("rz", 3);
fmt->addParam("s", 4);
fmt->addParam("convention", "position_vector");

fmt->addStep("helmert");
fmt->addParam("x", 10);
fmt->addParam("y", 20);
fmt->addParam("z", 30);
fmt->addParam("rx", -1);
fmt->addParam("ry", -2);
fmt->addParam("rz", -3);
Expand All @@ -10267,6 +10399,7 @@ TEST(io, projstringformatter_merge_inverted_helmert_with_opposite_conventions) {
fmt->addParam("rz", 3);
fmt->addParam("s", 4);
fmt->addParam("convention", "coordinate_frame");

fmt->addStep("helmert");
fmt->addParam("x", 10);
fmt->addParam("y", 20);
Expand All @@ -10291,6 +10424,7 @@ TEST(io, projstringformatter_merge_inverted_helmert_with_opposite_conventions) {
fmt->addParam("rz", 3);
fmt->addParam("s", 4);
fmt->addParam("convention", "position_vector");

fmt->addStep("helmert");
// fmt->setCurrentStepInverted(true); <== CAUSE
fmt->addParam("x", 10);
Expand All @@ -10316,6 +10450,7 @@ TEST(io, projstringformatter_merge_inverted_helmert_with_opposite_conventions) {
fmt->addParam("rz", 3);
fmt->addParam("s", 4);
fmt->addParam("convention", "position_vector");

fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", 10);
Expand All @@ -10341,6 +10476,7 @@ TEST(io, projstringformatter_merge_inverted_helmert_with_opposite_conventions) {
fmt->addParam("rz", 3);
fmt->addParam("s", 4);
fmt->addParam("convention", "position_vector");

fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", -10); // <== CAUSE
Expand All @@ -10366,6 +10502,7 @@ TEST(io, projstringformatter_merge_inverted_helmert_with_opposite_conventions) {
fmt->addParam("rz", 2);
fmt->addParam("s", 4);
fmt->addParam("convention", "position_vector");

fmt->addStep("helmert");
fmt->setCurrentStepInverted(true);
fmt->addParam("x", 10);
Expand Down
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