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Merge pull request #28217 from satyam102006:feature/dis-coarsest-scale

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[video] Add setCoarsestScale to DISOpticalFlow (Fixes #25068) #28217

### Description
This PR addresses issue #25068 regarding the number of scales in `DISOpticalFlow`.

Currently, `DISOpticalFlow` automatically computes the `coarsest_scale` based on the image size. While generally effective, this behavior can cause errors in specific use cases (e.g., mechanics/speckle pattern analysis) where high pyramid levels degrade quality.

This change introduces a manual override:
- Added `setCoarsestScale(int val)` and `getCoarsestScale()` to the public API.
- Updated `DISOpticalFlowImpl::calc` and `ocl_calc` to use the user-defined scale if set.
- Preserved the existing "automatic" behavior as the default (when set to -1).

### Changes
- **`modules/video/include/opencv2/video/tracking.hpp`**: Added virtual method declarations.
- **`modules/video/src/dis_flow.cpp`**: Implemented `set/getCoarsestScale` in `DISOpticalFlowImpl` and updated calculation logic.
- **`modules/video/test/test_OF_accuracy.cpp`**: Added `DenseOpticalFlow_DIS.ManualCoarsestScale` regression test.


Fixes #25068
This commit is contained in:
satyam yadav
2025-12-20 15:58:32 +05:30
committed by GitHub
parent 64755d0c3a
commit 2b42788803
3 changed files with 55 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files
modules/video/include/opencv2/video/tracking.hpp
+10
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@@ -678,6 +678,16 @@ public:
/** @copybrief getFinestScale @see getFinestScale */
CV_WRAP virtual void setFinestScale(int val) = 0;
/** @brief Sets the coarsest scale
@param val Coarsest level of the Gaussian pyramid on which the flow is computed.
If set to -1, the auto-computed coarsest scale will be used.
*/
CV_WRAP virtual void setCoarsestScale(int val) = 0;
/** @brief Gets the coarsest scale
*/
CV_WRAP virtual int getCoarsestScale() const = 0;
/** @brief Size of an image patch for matching (in pixels). Normally, default 8x8 patches work well
enough in most cases.
@see setPatchSize */
modules/video/src/dis_flow.cpp
+19 -4
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@@ -60,6 +60,7 @@ class DISOpticalFlowImpl CV_FINAL : public DISOpticalFlow
protected: //!< algorithm parameters
int finest_scale, coarsest_scale;
int user_coarsest_scale;
int patch_size;
int patch_stride;
int grad_descent_iter;
@@ -79,6 +80,8 @@ class DISOpticalFlowImpl CV_FINAL : public DISOpticalFlow
public:
int getFinestScale() const CV_OVERRIDE { return finest_scale; }
void setFinestScale(int val) CV_OVERRIDE { finest_scale = val; }
int getCoarsestScale() const CV_OVERRIDE { return user_coarsest_scale; }
void setCoarsestScale(int val) CV_OVERRIDE { user_coarsest_scale = val; }
int getPatchSize() const CV_OVERRIDE { return patch_size; }
void setPatchSize(int val) CV_OVERRIDE { patch_size = val; }
int getPatchStride() const CV_OVERRIDE { return patch_stride; }
@@ -228,6 +231,7 @@ DISOpticalFlowImpl::DISOpticalFlowImpl()
use_mean_normalization = true;
use_spatial_propagation = true;
coarsest_scale = 10;
user_coarsest_scale = -1;
/* Use separate variational refinement instances for different scales to avoid repeated memory allocation: */
int max_possible_scales = 10;
@@ -1367,8 +1371,14 @@ bool DISOpticalFlowImpl::ocl_calc(InputArray I0, InputArray I1, InputOutputArray
bool use_input_flow = false;
if (flow.sameSize(I0) && flow.depth() == CV_32F && flow.channels() == 2)
use_input_flow = true;
coarsest_scale = min((int)(log(max(I0Mat.cols, I0Mat.rows) / (4.0 * patch_size)) / log(2.0) + 0.5), /* Original code search for maximal movement of width/4 */
(int)(log(min(I0Mat.cols, I0Mat.rows) / patch_size) / log(2.0))); /* Deepest pyramid level greater or equal than patch*/
int max_possible_scale = min((int)(log(max(I0Mat.cols, I0Mat.rows) / (4.0 * patch_size)) / log(2.0) + 0.5), /* Original code search for maximal movement of width/4 */
(int)(log(min(I0Mat.cols, I0Mat.rows) / patch_size) / log(2.0))); /* Deepest pyramid level greater or equal than patch*/
if (user_coarsest_scale != -1)
coarsest_scale = min(user_coarsest_scale, max_possible_scale);
else
coarsest_scale = max_possible_scale;
if (coarsest_scale<0)
CV_Error(cv::Error::StsBadSize, "The input image must have either width or height >= 12");
@@ -1449,9 +1459,14 @@ void DISOpticalFlowImpl::calc(InputArray I0, InputArray I1, InputOutputArray flo
else
flow.create(I1Mat.size(), CV_32FC2);
Mat flowMat = flow.getMat();
coarsest_scale = min((int)(log(max(I0Mat.cols, I0Mat.rows) / (4.0 * patch_size)) / log(2.0) + 0.5), /* Original code search for maximal movement of width/4 */
(int)(log(min(I0Mat.cols, I0Mat.rows) / patch_size) / log(2.0))); /* Deepest pyramid level greater or equal than patch*/
int max_possible_scale = min((int)(log(max(I0Mat.cols, I0Mat.rows) / (4.0 * patch_size)) / log(2.0) + 0.5), /* Original code search for maximal movement of width/4 */
(int)(log(min(I0Mat.cols, I0Mat.rows) / patch_size) / log(2.0))); /* Deepest pyramid level greater or equal than patch*/
if (user_coarsest_scale != -1)
coarsest_scale = min(user_coarsest_scale, max_possible_scale);
else
coarsest_scale = max_possible_scale;
if (coarsest_scale<0)
CV_Error(cv::Error::StsBadSize, "The input image must have either width or height >= 12");
modules/video/test/test_OF_accuracy.cpp
+26 -1
View File
@@ -172,4 +172,29 @@ TEST(DenseOpticalFlow_VariationalRefinement, ReferenceAccuracy)
EXPECT_LE(calcRMSE(GT, flow), target_RMSE);
}
}} // namespace
TEST(DenseOpticalFlow_DIS, ManualCoarsestScale)
{
Mat prev = Mat::zeros(Size(320, 240), CV_8UC1);
Mat next = Mat::zeros(Size(320, 240), CV_8UC1);
randu(prev, 0, 255);
randu(next, 0, 255);
Ptr<DISOpticalFlow> dis = DISOpticalFlow::create(DISOpticalFlow::PRESET_FAST);
EXPECT_EQ(dis->getCoarsestScale(), -1);
Mat flow;
dis->calc(prev, next, flow);
EXPECT_FALSE(flow.empty());
int manual_scale = 3;
dis->setCoarsestScale(manual_scale);
EXPECT_EQ(dis->getCoarsestScale(), manual_scale);
dis->calc(prev, next, flow);
EXPECT_FALSE(flow.empty());
dis->setCoarsestScale(-1);
EXPECT_EQ(dis->getCoarsestScale(), -1);
}
}} // namespace