Delta Watch: Importing images for maps and backgrounds

This article is about viewing data in Delta Watch or using the web interface Delta Live!

Maps, images, photos, and drawings help to visualize and clarify it all.

Learn how to import maps and backgrounds and optimize web interface speed.

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Delta Watch: Importing images for maps and backgrounds


Both Delta Watch and Delta Live! can use images as backgrounds, either for maps or simply for clarification purposes. Within Delta Watch it is also possible to use CAD drawings directly. This article describes the steps to import and orientate all map and background images in an optimum way. Depending on the final use, image size and ratios become important.

Once imported and referenced, the images are global to Delta Watch and can be used anywhere, multiple times, even in multiple projects.

These images are separate from the Camera module that is available for Delta Live!

Supported formats
CAD-file: DXF, DWG


Loading image and CAD files is done in the module Administration > System configuration. For referencing images, use the section Map > Referencing. For any other image, use the Background images section.

Skip directly to the summary, or read on to learn more.

Map backgrounds for Delta Live!

Delta Live! uses OpenStreetMap instead of a referenced image. For this purpose, only approximate WGS84 coordinates would have to be specified for each sensor. Where and how to do that is not part of this article.

Using CAD files

CAD files can only be used as background for maps within Delta Watch. When using CAD files, the coordinate system configured in Delta Watch will need to match the coordinate system from the CAD drawing. No additional referencing is required (nor possible) when importing the CAD files.

Keep in mind that CAD files can contain many layers and lots of information (details that you might not want to see in the map view). Sometimes less is more. Meaning: keep the drawing simple with only a minimum of layers and information. Even though you can de-activate individual layers once imported, it is better to keep the original file clean. This also keeps the file size small and speeds up the loading process.

Below is an example of a CAD file used in a map view.

Images for use in map views and reports (Delta Watch only)

Within Delta Watch, maps are used to visualize the location and layout of sensors. By giving a sensor coordinates and orientating an image correctly, the sensor, and this could be any sensor, can be shown on a map. Further configuration allows one to assign icons, and an info box allows one to quickly assess the current state.

There is the map module where multiple maps can be viewed, but the same backgrounds can be loaded when viewing the results of an epoch in the network sketch or when creating reports.

The example below shows an image used for maps but loaded in the network sketch of the epoch module.

When using images in the actual MAP module within Delta Watch, it is possible to combine multiple images on a single map, possibly allowing you to cover a bigger area with more detail. When doing so, care needs to be taken when orientating each image so that any overlapping sections will match.

How it works

To correctly orientate, scale, rotate, and stretch an image, a relationship needs to be defined between the image and the coordinate system used in your project. This can be done in several ways:

  • Parametric transformation (four or six parameters)
  • Relational transformation (identical points method)

If the geo-referencing details of an image are known, then a four or six parameter reference method can be used.

If it is just an image, then one of the identical points methods needs to be used. With this method, either the corners of the image or specific pixels will be referenced to known coordinates. These could be actual coordinates, for example UTM based, or they could be based on the local coordinate system as Delta Watch can generate when setting up a project.

The below steps show how to use the identical points method. A minimum of 3 points needs to be used to do a correct referencing. The points should ideally be in a big triangle for best results.

Identical points method: Getting the pixel coordinates

To begin, you need to know the pixel position (X,Y) and your matching project coordinates. In such a case it is easiest to use the method where you match a pixel to a known observation.

    1. Open Delta Watch, and view your network sketch in the Epoch module.
    2. Select a few points that could be used, keeping in mind that best results can be achieved if the points are spread out and far away from each other. Write down their names.
    3. Open the image in an image editor that can show the X,Y pixel position. Most Windows installations come with a program called Paint that can be used for this.
    4. On the image, locate as good as possible the pixel that is closest to one of the earlier selected observations. Write down the X,Y pixel position. See screenshot of this process.
    1. Repeat for the remaining points. Close the image editor when finished.
    2. In Delta Watch, navigate to Point and limit management > Points.
    3. Find here the same points, and write down their Easting and Northing values. Two decimals should be sufficient. See the image below for an example.


    NOTE: Pixel position X,Y = Point coordinate E,N

    Import and reference the image

    With the relation between pixels and coordinates at hand, the image can be imported and referenced.

    1. In Delta Watch, navigate to Administration > System configuration, and locate the item Map > Referencing.
    2. Click on Add [Add]  to import the image. The name can be adjusted.
    3. Under Referencing, select the method to be used, in this case: Identical points.
    4. Select the first entry and Edit [edit], entering the first set of pixels and coordinate pairs.
    5. For the remaining items, use Add [Add] to enter them.
    6. Save the edits by clicking the Apply button.

    The image is now ready to be used. A quick check to see if the referencing is correct is to load it as a background view in the Network sketch of an epoch. Or you can configure a map under View configuration in this section and place all points on it. See the example below for a result of this.

    Backgrounds for geotechnical sensors, overviews, and Delta Live!

    This is the second category of images that can be used in Delta Watch and also Delta Live!

    Various modules under the Project management section can use these images simply for clarification and visualization purposes. These backgrounds are not referenced. Sensors are simply placed on them on a convenient position.

    If using Delta Live!, then an image and a logo can also be loaded in the Project area. These will be shown on the dashboard when selecting a project.

    But before the images can be used in these modules, they need to be loaded into Delta Watch. Once an image is loaded, it can be used and reused multiple times.

    At this point it is important to think of where the image is going to be used:

    • In a geotechnical sensor module in Delta Watch
    • In an overview for Delta Live!
    • In a report

    Depending on the use, it is good to take into account the required detail and possible zoom levels.

    File size

    Images with a lot of detail often have a big file size and thus will take longer to load, especially when using Delta Live! on a mobile device.

    A big file size often suggests a big image, and in Delta Live!, the space on screen is limited, and so the image will be zoomed-to-fit. Any initial detail might be lost.


    Dimensions and ratio: Geotechnical sensor modules

    Images used in these modules ideally have a width:height ratio within 5% of 4:3. If not, then the picture might show stretched or otherwise deformed on screen within Delta Watch itself.

    In Delta Live!, the image will show correctly, but the zoom level is adjusted to fit in the available space which has the ratio of 4:3.

    A good starting point is to make initial images no bigger than 800 x 600 (W x H). Even with a high-resolution monitor this is more than sufficient to be used within Delta Watch. Even 600 x 480 would still look good.

    If the image is for Delta Live! and some level of zoom is required without losing too much detail, then a size of 1200 x 900 is a good next size up. For Delta Live!, the ratio is less important, but file size might matter.


    Dimensions and ratio: Overview (image)

    Although this module is mostly for Delta Live! purposes, and images are correctly displayed in the web interface, it is still good to consider the dimension of the image to be used.

    A typical landscape image will initially show very small within Delta Live!, but you can zoom. In the same module in Delta Watch, it will show deformed, as the image is stretched-to-fit the available space. Depending on your screen, this might work out okay.

    The main factor to consider is level of detail and thus file size. Keep the file size small, and it loads faster when using Delta Live!


    Dimensions and ratio: Other images

    When using Delta Live!, it is possible to show a logo for the web interface and an image for each project.

    Logo Should be a small image with maximum dimensions of 300 px for both width and height.
    Project image Can be any shape, and for fast results, should be no bigger than 800 px in either width or height.


    The example below shows both logo and project images in Delta Live!

    Loading the background images

    1. Navigate to Administration > System configuration, and select the section Background image.
    2. Under Image configuration, click on Add [Add].
    3. In the following dialog box, browse for the file and adjust the name if required. This can also be adjusted afterward using the Edit  [edit] option.
    4. Close the dialog box, and Apply the changes. Repeat for any other images.

    To summarize

    • CAD files can be used for MAP backgrounds, but keep them simple and small.
    • Supported file formats: JPG, JPEG, TIF, TIFF, BMP, PNG, GIF, DWG, DXF
    • Images are loaded in the module Administration > System configuration.
      • To reference an image, use the section: Map > Referencing.
      • For use as a normal backgound, use the section: Background image.
    • Images for use in maps
      • Need to be referenced
      • When using the identical points method
        • Pixel X,Y = Coordinate E,N
        • Minimum of 3 points needs to be defined, preferably far apart in the shape of a big triangle
      • Multiple images can be combined in one map
      • Image size and ratio is not important—level of detail when zooming is
    • Images for use with geotechnical modules within Delta Watch should
      • Have a ratio matching 4:3 (W x H) closely
      • Be kept small, like 600 x 480 or 800 x 600
    • Images for use with geotechnical sensors within Delta Live!
      • Could have any ratio but will initially show zoomed-to-fit on screen
      • Be kept small to load faster
    • Images for overviews
      • Can be any size and dimension
      • Are best suited for use in Delta Live! only
      • Should be kept reasonably small, depending on the requirement to zoom/pan within the web browser