Digitizing Channels =============================== General ------- TWW has a wizard to correctly build channels and connect them to wastewater structures respectively to wastewater nodes or other reaches (building up the topology for waste water nodes and reaches). See the :ref:`wizard` chapter. Select the **Wizard** button, then click **Start Data Entry** and choose **Reach** in the pull down menu. .. figure:: images/wizard_data_entry.jpg .. figure:: images/wizard_data_entry_reach.jpg .. attention:: Start digitizing in the direction of the flow by starting with the **from manhole node** and finishing with the **to manhole node**. Digitizing ---------- * In digitizing mode the cursor will automatically snap to the nearest wastewater node or reach. When left clicking a line starts to draw. .. figure:: images/wizard_data_entry_reach_with_new_cursor3.jpg * With further left clicks anywhere you can define intermediary points of the reach progression. You can also directly select another manhole to draw a straight channel. * It is possible to use the **Advanced Digitizing** tools together with the wizard. .. figure:: images/wizard_data_entry_reach_with_new_cursor2-3.jpg * You finish digitizing the line by right clicking. This will make the **vw_tww_reach** feature attributes window appear and you can start adding data in the **General** tab: .. figure:: images/wizard_reach_form.jpg .. note:: Keep in mind that the finishing point of the line is the last point where you **left** clicked. Thus, for digitizing a simple line with 2 points you need two **left clicks** to digitize the line and one **right click** to finish the line digitizing. * Control the snapping to wastewater nodes or other reaches in the fields **rp_from/to_fk_wastewater_networkelement** .. note:: If you do not enter an `identifier` (reach-identifier) in the General tab, TWW will enter the `obj_id` also as identifier (you can change later). As default, the `identifier` of the reach is also the `ws_identifier` of the channel. As default, the reachpoint-identifier is set to the reachpoint-obj_id. .. note:: See :ref:`reach_geometrysync` for automatic reachpoint levels when snapping to wastewater nodes with level. * For the profile type you will get a list of defined profiles. You can edit the pipe profiles in **pipe_profile** table (layergroup Wastewater Structures). .. figure:: images/wizard_reach_form_profiletypes.jpg * When finished, then click the **OK** button. * Save the information of this layer by stopping the data entry wizard. .. figure:: images/stop_data_entry.jpg .. note:: The standard-fields on the **General** tab (and only those fields) do reuse the last entered attribute value when you add new reaches with the wizard. The QGIS option **Reuse the last entered attribute values** and the default values have no influence on these fields. * You can re-edit your object selecting the edit mode and then click with the info cursor on the object you want to edit. * If you do not select the edit mode, you can just look at the existing data. .. figure:: images/reach_info_reach3.jpg * For detailed information about editing see the :ref:`editing-data` chapter. Further attributes and classes ------------------------------ When a line object is digitized, a series of steps take place in the background in the TWW database: * a new object is added in the **wastewater structure** class (``wastewater_structure``) * a new object is added and linked in the **channel** subclass (``channel``) * a new reach object is generated in the **wastewater network elements** class (``wastewater_networkelement``) and its subclass **reach** (``reach``) * two new reach point objects are added and linked to the reach (**rp_from_node**, **rp_to_node**) .. _reach_geometrysync: Geometry synchronization ------------------------ When inserting a new reach using the wizard, the start and end points of the line geometry determine the level of the corresponding reach points (as shown in the pictures above). These values can be overwritten before saving. Upon saving, the level values `rp_from_level` and `rp_to_level` are used to define the Z value of the first and last vertex of a reach. When updating a reach, there are several cases: 1. The first/last reach geometry vertex was not changed, but the `rp_from_level` / `rp_to_level` was. In this case, the level value `rp_from_level` / `rp_to_level` is used to set the Z value of the first / last vertex of the reach 2. The first/last reach geometry vertex was changed, but the `rp_from_level` / `rp_to_level` was not. In this case, the QGIS variable `@tww_update_lvl_by_geom` defines whether the `rp_from_level` / `rp_to_level` is overwritten by the Z value of the first / last vertex of the reach 3. Both the first/last reach geometry vertex and the `rp_from_level` / `rp_to_level` were changed. The `rp_from_level` / `rp_to_level` take precendence 4. Neither the first/last reach geometry vertex nor the `rp_from_level` / `rp_to_level` was changed. No changes occur Synchronization of levels works also for intermediate points (points between the reachpoints), if you snap while digitizing to 3d-points on another layer (e.g. a textfile as result of gps-measurement with x,y,z coordinates added to the QGIS-project). Be aware, that you have then a full 3d-reach, but on the export to INTERLIS these intermediate-levels will be lost, because VSA-DSS version 2020 does not support 3d for reach-geometry. Digitizing flushing nozzle --------------------------- .. versionadded:: 2025.0 TWW is configured to digitize flushing nozzles as structure part of the channel. You can digitize a flushing nozzle * starting on the Feature Attribut window of vw_tww_reach with tab **Structure Parts**. Add point child feature and digitize the point on the map. Or * create a new point on vw_flushing_nozzle and choose the connected channel for field fk_wastewater_structure on the map. .. note:: A flushing nozzle is connected to a wastewater_structure, but it's geometry is totally independent of the wastewater_structure-geometry. If you move the channel, you have to move the flushing nozzle manually.