Use Case: Base Layer
Summary
- Scope: Base Layer
- Level: User Goal
- Actors: App User
- Brief: User imports a picture to use as a background.
- Assignee: Lukas
Scenarios
- Precondition:
- User has opened the app and selected the base layer.
- The user has an orthophoto or site plan and knows the real length of a flat part of the orthophoto (e.g. length of house's roof).
- Main success scenario:
- Background Image: User successfully imports an orthophoto or site plan to be used as a background by selecting the option to
- import a picture to Nextcloud or
- by choosing an image from Nextcloud.
- Rotation: The user chooses where north related to the screen is by choosing the angle in degrees it should be rotated by.
- Autoscaling: The user tells real lengths of lines (on flat land) so that we know how big this image in reality is.
- Offset: The user chooses a horizontal or vertical offset of the background image.
- Map Bounds: The user draws a polygon telling the app where the borders of this image are (these boarders are stored in the map and not subjective to "alternatives").
- Background Image: User successfully imports an orthophoto or site plan to be used as a background by selecting the option to
- Alternative scenarios:
- User accidentally replaces the ortophoto with another image or wrongly put a line in the polygon and presses undo to correct the mistake.
- Error scenario:
- User attempts to select a file that does not exist. The app displays an error message, asking the user to choose a different file.
- User attempts to import a file that is not a supported image format or is corrupted. The user is prompted to choose a correct image in one of the supported formats instead.
- Postcondition: The user's selected background image and map bounds are used for further planning.
- Non-functional Constraints:
- Support for multiple image formats
Out of Scope
Alternatives are not supported for border polygon/georeferencing.
- User selects an (additional) alternative image.
- The user scales the image, so that it fits to prior georeferencing.
- The user chooses an orientation of the picture, i.e., rotate the image to where north already is to fit prior north orientation
- The user can switch back to the original image.
- The user later (after changes in other layers were already done) finds that the polygon, the orientation or the georeferencing contains a problem:
- The app automatically saves the current version of the map.
- The user corrects the polygon, the orientation or the georeferencing.
- The database gets rewritten with the new geometric data. (No undo available but the user can load the previous version.)