Feature Description
Tie points are homologous image points that can construct a stereo model or establish the connection between adjacent models (images). Generating tie points helps to provide accuracy during geometric correction to ensure the spatial consistency of images.
Parameter description
| Parameter name | Parameter interpretation | Parameter type |
| Dataset |
Displays the dataset where the image used for generating tie points is located. Not editable. |
DatasetMosaic |
| Input image type | Select the type of image used for generating tie points. The default is Panchromatic Image. It can also be switched to Multispectral Image, Forward-looking image, Rear-view image or Front view and rear view image as needed. | ComboBoxImageType |
| Reference adjustment file |
Based on existing adjustment file information, align new tie points close to the accuracy of existing tie points. Use the Add and Delete buttons on the toolbar to conveniently manage multiple reference adjustment files. The reference adjustment file is obtained from the Block Adjustment function. |
ReferenceFileData |
| Error threshold |
The error threshold for eliminating gross errors in image matching. The value range is [0, 40], with a default of 5 (unit: px). During image matching, the least squares method is used to fit result points, removing points greater than the error threshold. A larger threshold retains more tie points but increases the probability of retaining erroneous points. |
Double |
| Point distribution mode |
Select the point distribution mode. Two modes are provided: Conventional and Uniform. The default is Conventional.
|
PointDistributionMethod |
| Number of blocks in column direction |
Available when Conventional is selected in Point distribution mode. The number of blocks each overlapping region is divided into in the column direction. The default value is 4. |
Integer |
| Number of blocks in row direction |
Available when Conventional is selected in Point distribution mode. The number of blocks each overlapping region is divided into in the row direction. The default value is 4. |
Integer |
| Matching method |
Available when Conventional is selected in Point distribution mode. Six matching methods are provided. Choose based on data characteristics and requirements. Among them, AFHORP and RIFT support multimodal data matching; CASP and DEEPFT are based on deep learning and require additional AI model configuration and CUDA environment installation; generally, MOTIF, CASP, or DEEPFT are recommended.
|
ImageMatchMethod |
| Intra-block maximum |
Available when Conventional is selected in Point distribution mode. The maximum number of points retained in each image block during image matching. The value range is [1, 2048], with a default of 256. |
Integer |
| Number of seed points |
Available when Uniform is selected in Point distribution mode. Set the number of seed points for homologous point matching on each scene image. The value range is [64, 6400], with a default of 512. When the image texture is poor, it is recommended to increase the number of tie points to match enough points and improve the quality of subsequent imagery. |
Integer |
| Seed point search |
Available when Uniform is selected in Point distribution mode. Set the method for searching seed points. The default is Grid center point.
|
SearchSeedPointMethod |
| Template size |
Available when Uniform is selected in Point distribution mode. Set the interval size between seed points. The value range is [1, 256], with a default of 40 (unit: px). The larger the template, the more reliable the searched points, but the longer the time taken. |
Integer |
| Search radius |
Available when Uniform is selected in Point distribution mode. Set the search radius for seed point image matching. The value range is [0, 256], with a default of 40 (unit: px). The larger the search radius, the larger the matching range and the longer the time taken. |
Double |
| Semantic culling of non-ground points | Not checked by default. When checked, based on AI semantic technology, tie points in cloud areas and building areas are automatically removed. | Boolean |
| Cloud area | Available after checking Semantic culling of non-ground points. Checked by default, meaning tie points within cloud areas are automatically removed based on the set dataset. If not checked, tie points in cloud areas are retained. The dataset must contain the ImageName field, and the name must correspond to the current image name to be processed. | Boolean |
| Dataset |
Displayed after checking cloud area. Not editable. If the workflow is for DOM production, the Set Image Path cloud amount data is used. If the workflow is for DSM production, the Set Image Path (DSM/DEM) cloud amount data is used. |
DatasetVector |
| Building area |
Available after checking Semantic culling of non-ground points. Checked by default, meaning building areas are automatically identified and tie points in those areas are removed. If not checked, tie points in building areas are retained. |
Boolean |
Output Result
In the Control Point datasource, a TiePoint vector point dataset is generated.
Related Topics
Generate Ground Control Points
References
[1] Chen, P., Yu, L., Wan, Y., Pei, Y., Liu, X., Yao, Y., ... & Zhang, Y. (2025). CasP: Improving Semi-Dense Feature Matching Pipeline Leveraging Cascaded Correspondence Priors for Guidance. In Proceedings of the IEEE/CVF International Conference on Computer Vision (pp. 28063-28072).