Jak nejlépe pracovat s velkými vrstvami prvků

Anonymous User

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Pracuji na získávání dat z obrovské vrstvy prvků stezek pro zobrazení v aplikaci pro iOS. Abych mohl zobrazit jednotlivé stezky různými barvami, uvažoval jsem o použití #iOS SDK filtračních funkcí k filtrování dat pro každou stezku a zobrazení filtrovaných dat stezky jako jiné vrstvy prvků. Vrstva stezek je obrovská, takže vidím, že aplikace iOS potřebuje chvíli na zobrazení dat. Jak mohu tuto filtraci provádět vzdáleně? Mohu vytvářet nové vrstvy prvků na arcgis z jiných vrstev vzdáleně? Lze to provést v #ASP.NET Core webové aplikaci? A obecně, jaký je nejlepší způsob, jak pracovat s velkými datovými sadami v mobilních aplikacích.<\/P><\/BODY><\/HTML>

Nicholas-Furness

Hi.

There appear to be a lot of questions here, only some of which are relevant to the Runtime SDK for iOS. But I'll try to provide some guidance…

Firstly, can you explain what you mean by the "iOS SDK filter functions"? Are you referring to definitionExpression?

Typically, you might draw a set of data in different colors by using an AGSUniqueValueRenderer, but that might only work if you are not displaying a huge number of trails at a time. See this sample.

Which leads to my second question. How are you displaying these trails? Will you zoom out to display hundreds of trails at a national level, or do you focus in on specific trails or areas with just a small set of trails visible at any one time?

In the latter case (i.e. you have a set of trails that you know you will be working with), you could set the AGSServiceFeatureTable's featureRequestMode to manualCache. You would then populate the local in-memory AGSServiceFeatureTable using populateFromServiceWithParameters() and set an appropriate whereClause on the AGSQueryParameters. This will make the network request once, and then display the features from memory. As you zoom and pan around, your app won't make network requests to refresh or reload the data. Other featureRequestModes might end up displaying from memory, but features are not aggressively cached so panning and zooming is likely to result in repeat requests (see the bufferFactor property for some control). This way, you have complete control over when the features are retrieved from the service.

Setting the featureRequestMode to manualCache and calling populate with a whereClause is fundamentally very similar to using definitionExpression with the default featureRequestMode, except that you have total control over how long features are cached locally and when network requests are made.

As for your other questions:

• I'm not sure what you mean by "ASP.Net Core webapp".
• You can create Feature Layer Views of a hosted feature service. I do not know how you would create and manage those remotely and it doesn't sound like it would solve your issue.
• The best way to deal with large data sets depends on a lot of variables to do with the data - these considerations will have an impact on how you might publish your data and how you might access it (e.g. the populate approach above):
  • Will you need to see it all at once when zoomed out? If so, you could publish the feature layer to a tiled image service and display the tiles when zoomed out.
  • Will you be editing it? If not, you could publish a separate generalized layer for use when zoomed out.
  • How reliable is your network connection? If it's slow or variable, you could consider the populate approach above or you might consider generating a Mobile Map Package with ArcGIS Pro and using that.

Hope some of this helps, but I'd need to understand more about what you're trying to achieve.