Vector union
Version 1 (Redmine Admin, 11/23/2011 04:44 pm)
| 1 | 1 | This technical note shows a process for overlaying two polygon vector layers. The layers used here are the tundra and swamp layers from the Alaska sample data set. |
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| 3 | 1 | *Plugins* : *fTools*. This is a core plugin and should be installed by default. |
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| 4 | 1 | ||
| 5 | 1 | ---- |
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| 6 | 1 | ||
| 7 | 1 | To complete this process, first the two vector layers into QGIS. This example is using @swamp.shp@ and @tundra.shp@. |
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| 8 | 1 | ||
| 9 | 1 | [[file_swamp_tundra.png|700px]] |
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| 10 | 1 | ||
| 11 | 1 | <small>Alaska project showing tundra (purple) and swamp (grey)</small> |
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| 12 | 1 | ||
| 13 | 1 | To open the union dialogue, select *Vector* → *Geoprocessing tools* → *Union* |
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| 14 | 1 | ||
| 15 | 1 | [[file_union_tun_swa.png]] |
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| 16 | 1 | ||
| 17 | 1 | <small>Union tool dialogue box</small> |
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| 18 | 1 | ||
| 19 | 1 | Fill in the box, and be a little patient. |
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| 21 | 1 | [[file_tun_swa.png|700px]] |
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| 23 | 1 | <small>Resulting shape file showing the union of the tundra and swamp data</small> |
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| 24 | 1 | ||
| 25 | 1 | ---- |
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| 26 | 1 | ||
| 27 | 1 | *Notes* |
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| 28 | 1 | * using the select button, layers that are not open in QGIS can be used in this analysis. |
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| 29 | 1 | * remember, that vectors can only display point, line or polygons. |