Managing Scenario Comparison

Hello! I'm trying to use the scenario comparison to check any changes between the model and the actual pipes.

I have a wtg project from 2021 and in the last days the team finish the actualization of the shapefiles on GIS containing new pipes and interventions on the city, i'm tring now to create a child scenario and using model builder with the new shapefiles and then use the Scenario Comparison, but when i make the new import of the shapefiles on child scenario, all pipes on my base scenario got 152mm and Ductile Iron.   

Does anyone know a method or a tool to make this? 

  • Hi Fabio,

    If you are adding new pipes/nodes to the model, it is best to add them to the base scenario that uses the base alternatives, so that the child scenarios inherit the settings. Otherwise if you add them in a scenario that uses child alternatives, the parent alternatives (and the scenarios that use them) will use the default settings of elements per the Prototypes, which is why you see the default 152 mm diameter pipes. This situation is described in the following related article: Elements seemingly changing to default settings, zero status, inactive

    If you are trying to update existing elements with ModelBuilder, ensure that you select the correct key field (in the field mapping step) so that ModelBuilder knows to import the changes to the existing corresponding elements instead of creating new ones.

    If this does not help, please tell us a bit more about what you are trying to do and the steps you took to encounter the problem.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

    Answer Verified By: Fabio Lobo Araujo 

  • Hi Jesse! Sorry if it wasn't that clear. I have a model that was calibrated in 2021, since then some changes have been made in the field, these updates were never inserted into the model.
    Now I have shape files containing all these updates with the rest of the network.
    My idea would be to import this new shape file in a child scenario, and then use the scenario comparison tool to check what and where are these updates on the network. Would this work? I would need a child scenario without any network to be able to import the new shape file, and when I delete any tube in the child this is reflected in the base. The same happens if I try a base scenario with another base.If I import a new shape file in another scenario, will I lose the connection that allows the scenario comparison tool to work right? Is there another way to to this checks between new shape files and old model files?

  • Hi Fabio,

    Can you tell us a bit more about these changes that were made and the shapefiles you have?

    When you say the changes were made, do you mean existing elements were changed (for example new diameter and roughness) or do you mean new pipes were added? (or both?)

    When a new element is added to a model, it will exist in all scenarios, and when it is deleted, it is deleted in all scenarios. You can use the Active Topology alternative to turn elements on or off with the "Is Active" property. Meaning, if the child scenario has new pipes that did not exist in the parent scenario, you can make those new pipes active in the child scenario and inactive in the base  (inactive pipes still exist but are treated as if they are not there). You could use ModelBuilder with a child scenario using a child active topology alternative to import the newly added pipes, so that the default status of inactive is seen for the parent scenario (where those pipes did not exist yet) However any imported attributes (physical data like diameter, etc, for new elements or for existing elements mapped via the "key field") imported when using a child physical alternative, will have default values (as previously mentioned) in scenarios that use the parent alternative. See more here: Active Topology Management

    Scenario comparison is used to check differences between two scenarios, for elements that exist in both scenarios. Do you want to be able to view newly added elements and changed elements after importing your Shapefile? If you used active topology to manage elements that are present in one scenario but not another, Scenario Comparison will show the difference in the "Is Active?" property.

    You can find more practical information and tips on scenarios and scenario comparison in these articles:

    Ideally if the model is kept in sync with a GIS, you would use the Snapshots feature to compare changes between the model and the connected GIS (new elements, elements being removed, changed elements). However, this requires you to use this feature in an initial baseline ModelBuilder run. See more here: Using ModelBuilder snapshots to help track changes and updates between source file and model file

    If this does not help, please provide a bit more information about what you are trying to do so we can help you.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

    Answer Verified By: Fabio Lobo Araujo 

  • Hello Jesse! 

    I was reading the articles, specially the: Using ModelBuilder snapshots to help track changes and updates between source file and model file, and what i was trying to do it's exactly what Snapshots do! But in my case i don't have snapshots. The model was deliver by other company and the modeller didn't use any snapshots at all. In this case did you know another way to check those differences?

  • Right, the model would need to have been built with the Snapshots feature enabled, in order for it to establish the baseline to compare to in future updates.

    If Snapshots cannot be used, Scenario Comparison may work for what you need to do. If you are using ModelBuilder to update existing elements, ensure that you have a child scenario set up with child alternatives for the different types of data that ModelBuilder will be updating. For example if diameter and roughness are being updated, you'll want to make sure that the child scenario is using a child physical alternative.

    In your original post back in October of last year, you mentioned that you tried this but pipes in the base scenario were reverting to default physical properties. This suggests that the base scenario may have been set to use a new base physical alternative, or possibly ModelBuilder imported everything as new elements instead of updating existing elements (which could be due to an issue with the Key Field). If this issue is still occurring, we'll need more details to determine why it happened and how you can prevent it from happening. For example you could provide a copy of the model and screenshots of the ModelBuilder Run that was used, or a copy of the ModelBuilder Connection file (.MBC). See:


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

    Answer Verified By: Fabio Lobo Araujo