# Optimizing Maps, tips and tricks

- As `test_user1` view the `Boulder` map and click on the `layer menu` in the top-left corner.

    ![image](./img/adv_map_1.png)

- Expand the datasets list and highlight the `Mainrd` one. Click on the `property tool`

    ![image](./img/adv_map_2.png)

- Switch to the `view` options tab, you will notice a few settings that can be tweaked on each dataset to improve the map quality or rendering speed

    * **Format**: This allows us to set the output media type from the ones supported by the spatial service.
    * **Tile Size**: This value is usually set to `256x256` pixels, GeoNode sets them to `512x512`. This value allows us to send tiled requests to the `Tile Service`. A larger size allows GeoNode to reduce the number of requests per dataset.
    * **Visibility Limits**: Has the same effects as the `Scale Denominator` rules on the styles. The two options are always applied independently.
    * **Transparent**: When `enabled`, it allows the server to render the `alpha` transparent channel where no data is present.
    * **Use cache options**: decides whether or not to use the tile service (`WMTS`) or (`WMS`).
    * **Single Tile**: When `enabled` GeoNode won't create tiled requests for this dataset but will create a single tile with the dimensions of the current viewport. In some cases, this might speed up the rendering by drastically reducing the number of requests. Be aware that `Single Tile` will never use the server cache.

    ![image](./img/adv_map_3.png)

- For this dataset, let's change the output format to `jpeg+png8` and set the `Min Scale` to some value to hide the dataset at higher zoom levels.

    ![image](./img/adv_map_4.png)
    
    _The JPEG+PNG8 output format will allow GeoServer to use JPEG compressions on images and PNG8 on transparent tiles. This will reduce the size of the images, speeding up the dataset, but it will also reduce its quality. That option is typically only useful on raster imagery._

- You can also edit other available datasets:
    - Change the output format to `PNG8`, on vectorial datasets with few colours (like in the above case). This will greatly reduce the size of the images, resulting in an overall speedup of the dataset.

    - Open the `Network` tab of the browser and inspect the `ows` requests. Notice the different output formats of the requests for the dataset. Do some tests by changing the output format, and notice the difference between the sizes and timings of the outcomes.

    - Also, by expanding the `Headers` section, you will see how the `geowebcache` responses match with a `Cache HIT`, meaning that we are correctly asking for cached tiles to the `WMTS` service


It is also possible to select and edit the default style of a dataset from a map by clicking on the `dropper` icon as shown below.

  ![image](./img/adv_map_5.png)

- When changing the settings for datasets on a map with many overlays, it is good practice to temporarily deactivate the other layers to speed up the work by avoiding loading all of the layers every time

- Let's edit the options for the `Mainrd` dataset. Click on the `Filter` option, and check the `Area of Interest` options

- Change the `Filter Type` to `Polygon`, and the `Geometry Operation` to `Contains`. Draw a `polygon` on the map and click `Apply`

    ![image](./img/adv_map_6.png)

- Try modifying the `Geometry Operation` to `Contains` and note the differences

    ![image](./img/adv_map_7.png)

- Save the filter and go back to the map. Notice that a small `filter icon` now appears near the dataset name, and the map only shows the filtered features

    ![image](./img/adv_map_8.png)

- You can optionally persist the changes on the map.

## Attributes Media Types Rendering on GetFeatureInfo

The `GetFeatureInfo` is a special operation in the `OWS` protocol that allows us to query a dataset on a specific position to get back the values stored on the backend.

In the case of a `VECTORIAL` dataset, the outcome of the `GetFeatureInfo` is basically a set of `records` (i.e. `key-value` pairs where the `keys` are the `attributes` from the `schema` below).

In the simplest use case, the outcome of the `GetFeatureInfo` is a plain text report of the list of `attributes` along with the `values` of that specific `location`. As you can imagine, the values can be almost anything, even references to external `links` or `media contents` (like `images`, `videos` or `audios`).

GeoNode can also apply, eventually, an `HTML template` to the `GetFeatureInfo` outcome. That means that GeoNode can render the output as `HTML` content.

From the dataset metadata, there's the possibility to `edit` such a `template`. In particular, there are two different ways to enable it:

1. Basic: GeoNode will present the available `attributes` list, allowing the user to change the order, visibility, and `media-type` on each attribute.
2. Advanced: GeoNode will present a `rich-text` editor panel allowing the user to define its own custom `HTML template`.

In this section, we will see how the `basic` one works by defining and editing a new `empty dataset`.

- Let's first create a new `empty dataset` with the following attributes:

    * `geometry type`: `Polygon`
    * `image`: `String`
    * `video`: `String`
    * `audio`: `String`
    * `href`: `String`

    ![image](./img/adv_map_9.png)

- Edit the layer data and add a new `polygon`

    ![image](./img/adv_map_10.png)

- Fill the `attributes` with some links, e.g.

    * `image`: `https://asia.olympus-imaging.com/content/000107506.jpg`
    * `video`: `https://www.youtube.com/watch?v=-ucUFBTUYLI`
    * `audio`: `https://samplelib.com/lib/preview/mp3/sample-3s.mp3`
    * `href`: `https://geonode.org/`

    ![image](./img/adv_map_11.png)

- Save, click on the polygon, and look at the results

    ![image](./img/adv_map_12.png)

- Now go back to the dataset details, edit the metadata, and move to the `Attributes` tab. Change the contents as shown in the figure

    ![image](./img/adv_map_13.png)

- Save, visualize the dataset, and click on the polygon again

    ![image](./img/adv_map_14.png)

    ![image](./img/adv_map_15.png)

#### [Next Section: Charts and Widgets](MAPS_CHARTS_WIDGETS.md)