Check Overlaps and Gaps
ពិនិត្យស្រទាប់ polygon រកកំហុស topology ទាំងការត្រួតគ្នា និងចន្លោះទទេ។
- រកឃើញនៅឯណា
- Processing ▸ Toolbox ▸ KGA Toolbox ▸ KGA Topology ▸ Check Overlaps and Gaps
- លេខសម្គាល់ algorithm
- kga:checkoverlapsandgaps
- ប្រភេទឧបករណ៍
- Batch algorithm (runs on the GUI thread — it adds error layers to the project)
ទិដ្ឋភាពទូទៅ
Checks polygon layers for the two errors that matter in a parcel or land-use dataset: polygons that overlap each other, and enclosed gaps left between them.
Overlaps are reported for every pair of polygons whose intersection has an area — within one layer and, when several layers are supplied, between them as well. Gaps are the enclosed holes left once every input feature is dissolved together.
When errors are found, two memory layers are added at the top of the Layers panel and symbolized so you can see them at a glance; Open Error Inspector then walks you through them one by one.
ប៉ារ៉ាម៉ែត្រ
| ឈ្មោះ | ប្រភេទ | តម្លៃលំនាំដើម | ការពិពណ៌នា |
|---|---|---|---|
| Input polygon layer(s) | Multiple vector layers (polygon) | — | The layers to check. Non-polygon layers are skipped with a warning. The first layer's CRS is the one the check runs in; the rest are reprojected to it. |
| Use selected features only (when a selection exists) | Boolean | False | On, a layer with a selection contributes only those features; a layer with no selection still contributes all of them. |
| Check overlaps | Boolean | True | |
| Check gaps | Boolean | True | |
| Ignore errors smaller than (square map units) | Number | 0.000001 | The sliver threshold. Errors at or below it are dropped. |
| Ignore gaps larger than (square map units, 0 = no limit) | Number | 0.0 | Upper bound for gaps, so a genuine untouched area — a lake, a forest block — is not reported as an error. 0 means no limit. |
របៀបប្រើ
- Load the polygon layers. Put the one whose CRS the check should use first.
- Open KGA Topology > Check Overlaps and Gaps.
- Pick the layers, and set Ignore errors smaller than to the precision your survey actually has — this is what separates a real overlap from floating point noise.
- If the dataset has legitimate untouched areas, set Ignore gaps larger than above the largest sliver you care about and below the smallest real void.
- Press Run.
- If errors are found, open Open Error Inspector to step through them.
លទ្ធផល
លទ្ធផលដែលប្រកាស
| ឈ្មោះ | ប្រភេទ | ការពិពណ៌នា |
|---|---|---|
| Overlaps found | Number | |
| Gaps found | Number |
អ្វីដែលអ្នកទទួលបាន
When errors are found, two memory layers are added to the top of the Layers panel:
- Topology Errors - Overlaps — one polygon per overlapping pair, fill
#FF8080with a red outline. Fields:error,layer_a,fid_a,layer_b,fid_b,area. - Topology Errors - Gaps — one polygon per enclosed gap, no fill with a
#FF8080outline. Fields:error,gap_id,area.
When no errors are found, a message box says so and any error layers left over from a previous run are removed from the Layers panel.
កំណត់សម្គាល់ និងដែនកំណត់
- Gaps that open onto the outer edge of the dataset cannot be detected. A gap is found as an interior ring of the dissolved geometry, so a void on the boundary of the study area is not enclosed and is invisible to this check.
- Areas are in the square map units of the first input layer, which also defines the CRS the check runs in. Both thresholds are in those units — square degrees if that layer is geographic, which is almost never what you want.
- The error layers are memory layers. They vanish when the project closes unless you save them.
- Invalid geometries are repaired before the check (
makeValid, falling back to a zero buffer). Features that cannot be repaired are counted in a warning and left out. - Every pair is compared, so the overlap check grows with the square of the feature count in dense areas. A large dataset takes time.