create a webmap using layer package in arcgis

#Create a webmap using layer package in arcgis pro

You define what transformation should be used when on-the-fly reprojection is required i.e. With this option, your source data and hosted feature layer data remain in the same projection. Option 1: Preserve the projection of your data but define a transformation that ArcGIS Online can use when performing on-the-fly reprojections of the hosted feature layer. When you publish a hosted feature layer from ArcGIS Pro, and you know people will use the hosted feature layer in maps that contain ArcGIS Online basemaps, you can do one of the following: If you publish Hosted Feature Layers with a different datum to your Web Map, the data may not align if a transformation cannot be correctly applied.

#Create a webmap using layer package in arcgis pro

But what coordinate system is stored against the layer being added, and what transformation is being applied? This is dictated by the coordinate system and transformations set in the Map Properties in ArcGIS Pro at the time of publish. Layers added to the ArcGIS Online Web Map Viewer and Scene Viewer will be reprojected on the fly to line up with the basemap. Publishing Hosted Feature Layers from ArcGIS Pro – Coordinate Systems and transformations at a service level If a coordinate conversion is required in Web GIS from WGS84 to GDA2020 then a transformation path of WGS84 > GDA94 > GDA2020 should be utilised.Transform all data to GDA2020 and republish to Web GIS in GDA2020 or a GDA2020-based projected coordinate system. Do NOT mix GDA94 and GDA2020 data in a web GIS as there will be an approximately 1.8m alignment error.Data will be published with GDA94 accuracy and coordinate transformations between WGS84 and GDA94 can be performed. If publishing for use in WGS84, project the data first using GDA2020 > GDA94 > WGS84.Create your own basemap in GDA2020 and use layers published in GDA2020.From a user data perspective on GDA2020 Esri Australia recommends: In most instances this will not be an issue as the generic basemap data is derived from many sources with varying positional accuracies. This introduces challenges where a composite transformation is not allowed, such as applying transformations to mosaic datasets.ĭata in the web map environment can be displayed against Esri basemaps and web scenes and other WGS84-based data. A composite transformation is available of WGS84 to GDA94 and GDA94 to GDA2020. The following diagram gives a representation of the relevant issue:Īt the time of writing in March 2021, there is no transformation between GDA2020 and WGS84 directly. Unfortunately, with the modernisation of the Australian datum to GDA2020 there is not a definitive relationship between GDA2020 and WGS84. Essentially, the problem presents itself as a misalignment of GDA94 or GDA2020 data when viewed in a WGS84 based projection. Although this has not presented significant issues to the end-user as data mapped in web maps typically had low accuracy – this is changing. That ‘Null’ parameter now creates a problem when projecting GDA2020 data to WGS84 Web Mercator as the differences between GDA94 datum (a static datum) and WGS84 (effectively, a dynamic datum) have increased over time. At this period both GDA94 and WGS84 were considered coincident as they were based on the same spheroid, with essentially the same origin.

The Web Mercator Dilemmaĭuring the early 1990s, the governing bodies defining the transformation parameters between GDA94 and WGS84 set the transformation as ‘null’. Failing to address these challenges may result in data misalignment. The de facto WGS84 in web GIS brings some challenges not unique to Australia or ArcGIS. It is also important to understand GDA2020 and its relationship with web GIS. When publishing data to web GIS you need to consider what spatial reference will be used to store the data at a service level, how the publishing process may affect it, as well as what transformations (or lack of) will be applied when the layer is displayed in a web map with a datum.

When you add layers to the Web Map Viewer, an on-the-fly reprojection is performed to align your data with the coordinate system of the basemap. Layers also have their own spatial reference and transformations defined at a service level. WGS 1984 Web Mercator (auxiliary sphere) is the spatial reference of basemap services in the default Esri basemap gallery, meaning this is the default web GIS coordinate system. In ArcGIS Online Map Viewer, all layers in a web map inherit the coordinate system of the basemap.