{"id":263322,"date":"2018-10-01T14:38:24","date_gmt":"2018-10-01T21:38:24","guid":{"rendered":"http:\/\/www.esri.com\/arcgis-blog\/?post_type=blog&p=263322"},"modified":"2020-03-26T09:05:54","modified_gmt":"2020-03-26T16:05:54","slug":"scale-dependent-multiple-datasources-for-a-single-feature-layer_multi-level-geography","status":"publish","type":"blog","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/mapping\/mapping\/scale-dependent-multiple-datasources-for-a-single-feature-layer_multi-level-geography","title":{"rendered":"Scale dependent multiple datasources for a single feature layer"},"author":5971,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"open","ping_status":"open","template":"","format":"standard","meta":{"_acf_changed":false,"_searchwp_excluded":""},"categories":[22941],"tags":[31361,241352,145432,241342],"industry":[],"product":[36571,36561],"class_list":["post-263322","blog","type-blog","status-publish","format-standard","hentry","category-mapping","tag-census","tag-data-source","tag-query-layer","tag-scale-dependent","product-arcgis-enterprise","product-arcgis-pro"],"acf":{"short_description":"A single feature layer with scale dependent datasources to create multi-level-geography map to understand an issue nationally and locally.","flexible_content":[{"acf_fc_layout":"content","content":"

There are sometimes when you want to have a multi-level-geography map, as seen above, where you want to visualize an attribute at national level as well as at regional or even at neighborhood level as you zoom to larger scales in order to reveal the same information in finer details. For example, the map above shows ‘vacant housing unit rate comparing to national average’ at state level and then as you zoom in you can see the same information at county level followed by at census tracts and all the way to block-group level.<\/p>\n

Traditional solution:<\/strong><\/p>\n

This might be something you have done many times before – the traditional approach to solve this problem is to use multiple layers, with mutually exclusive scale visibility range<\/a>, where each layer represents one geographic\/political unit such as states, provinces, divisions, counties, districts, tracts, blocks etc. And symbolize all layers using the same symbology. If you want, you can give it a try with this webmap<\/a> – when you open it, it shows 2010 population density at US state level, as you zoom in, you will see that it shows the same information at greater details – from states to counties to census tracts to block groups. Now, if you want to change symbology e.g. to symbolize them with a different color scheme, you will run into the problem that is described below.<\/p>\n

Problem:<\/strong><\/p>\n

The issue that we often run into with this approach is that it requires symbology set separately for each layer to begin with. And if you need to make any change to a symbol or change break values for a class breaks symbology, you need to keep repeating the same thing for all layers. It gets even harder when you want to share as a web layer and you want your end users to modify its symbology based on their needs.<\/p>\n

Solution:<\/strong><\/p>\n

ArcGIS Pro 2.2 introduces\u00a0view_scale parameter<\/a> in a query layer that allows you to vary where clause or selected fields or even table name in a SQL statement based on the current map scale. We will use that to read features from different tables based on map scale. Please note, in this case schemes for all these tables must be identical as it is the case in the webmap specified earlier.<\/p>\n

Steps:<\/p>\n