In ArcGIS Online Map Viewer, all layers in a web map inherit the coordinate system of the basemap. 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. Layers also have their own spatial reference and transformations defined at a service level. 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.
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.
It is also important to understand GDA2020 and its relationship with web GIS. The de facto WGS84 in web GIS brings some challenges not unique to Australia or ArcGIS. Failing to address these challenges may result in data misalignment.
When you work with spatial data in ArcGIS Pro, you add datasets as layers to a Map. The map has a defined spatial reference, and this is what ArcGIS Pro uses as it attempts to align your data to the map. It is important to understand how this behaviour works, how to ensure your data in a different datums have correct transformations applied, and what options are available to change default behaviours.
Australia has recently moved towards a new datum, the Geocentric Datum of Australia 2020 (GDA2020), to facilitate a more robust, accurate and capable datum that is more closely aligned with the expectations of a modern, connected Australia.
The introduction of a new datum impacts all areas of the software. Esri support for GDA2020 was progressively added as the datum parameters and associated transformation methods were released. All current releases of ArcGIS Pro (2.2 onward) and ArcGIS Desktop (10.6.1 onward) now support GDA2020, the associated projections, and transformations between it and GDA94.
An additional installation is required to support the NTv2 grid-based transformation methods released for GDA94-GDA2020.
GIS data must accurately represent real-world locations to be useful. To do this, you need a standard framework for defining location – a coordinate system. All spatial data utilises a coordinate system to position itself relative to your map and other data. However, coordinate systems are frameworks. They are models, spheroids, imperfect approximations of the shape of the Earth with all its bumps and curves as it changes with time. When working with spatial data you need to consider how a GIS positions this data against reality using coordinate systems.
By better understanding coordinate systems, you will be able to manage your data in a way that increases the accuracy of your maps and the work that you do with them. This blog is the first in a series taking a closer look at using Australian spatial references in ArcGIS. We will start by looking at geographic coordinate systems, projections, and transformations.
You’ve purchased an ArcGIS Student license; now, how do you to use it?
This is your one-stop-shop for getting up and running with your new ArcGIS for Student Use subscription. This blog will step you through each stage of the setup process, using the following FAQs as our guide:
Background: Sometimes users/publishers/ArcGIS Enterprise administrators reach out to GIS administrators that they cannot log in to ArcGIS Portal or the application is not reachable via browser. Users might observe that ArcGIS Server services are not working, or they cannot load hosted feature layers in their web maps. In those scenarios the GIS Administrator should do the following preliminary checks.
Background: GIS administrators are routinely required to do maintenance activities on their ArcGIS Enterprise High Availability setup. Examples of a maintenance activity can be: Installing Microsoft patches or Esri patches, or resizing instances etc. Before the maintenance is initiated, GIS administrators should know the exact status of the ArcGIS Enterprise setup so that a workflow can be finalized (that is, whether the application on the machine is assigned a Primary or a Standby role). If this is not taken into account, the architecture may become unstable. For example, if the Primary is shutdown first and then the Standby is shutdown, and the Standby is fired up and then the Primary, then the two machines may end up in a scenario where there is confusion as to which machine is the Primary machine.
Most organization would like to share their data with other organization’s department or expose their internal data to public community. Distributed collaboration allows you to quickly share data and content across organizations and individuals. Also, it provides the ability for users to leverage data from other organization, improve engagement, communication and decision making.
In any enterprise environment, it is crucial that services are able to restart/recover automatically in the event of disruption or failure. In the example of this blog post, this would be if there is a power outage or the server reboots unexpectedly.
When your services are not able to automatically recover, this can cause long outages for your users, especially if you are not actively monitoring your underlying infrastructure.