# Spatial reference systems AGOL scenes default to using the [Web Mercator spatial reference system](https://doc.arcgis.com/en/insights/latest/analyze/spatial-references.htm), with all default background map content also conforming to that. Unfortunately, the subsequent mixing of layers with differing spatial reference configurations is not supported. As such, any default background maps will be removed if, say, a mesh in EPSG:27700 (British National Grid) is introduced alongside. This behaviour contrasts to what can be expected when working inside ArcGIS Pro. It is possible to re-project an EPSG:27700 integrated mesh into Web Mercator, using the ‘Project’ geoprocessing tool found in ArcGIS Pro. Although this might take a notable amount of processing time to accomplish, the output will potentially be able to sit alongside any ArcGIS Online background content. If taking this route, you’ll obviously need to re-project any other data layer that you’re planning to use before introducing them into the AGOL environment. In most situations, it's going to be impractical and ineffective to apply the default background mapping within your project. ## Navigating the scene Scene navigation, within the Scene Viewer, is standard regardless of content. The middle mouse button controls the zoom extent, whilst the left and right mouse buttons, in conjunction with mouse movement, control panning and rotation. When applicable, clicking a distinct feature, within the current view, will open a pop-up menu showing relevant attribution. On the top-right of the UI, buttons enabling several further tools can be found. These include options for further adjusting the scene’s appearance, via the use of real-time daylight and weather data. ## Working with additional geospatial vector layers While your users may be happy just to view a raw OS 3D mesh, it’s more probable that you’ll want to combine this with other data sources to create your own unique narrative. Geospatial vector layers are an obvious source of additional detail, so we’ll cover this in detail in the following pages. The method for adding vector layers is no different from how you would add a mesh – you just choose what you need from your Content repository. Assuming everything is working correctly, these layers will then be added into your scene in the same manner. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.os.uk/os-downloads/upcoming-products/beta-products-information/os-3d-mesh-beta-product/getting-started-guide/importing-an-os-integrated-mesh-model-into-arcgis-online/spatial-reference-systems.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.