When you work solo as an IT administrator, you pretty much handle everything that tech touches, and sometimes that means keeping your maps as alive as the world they represent.
When you work solo as an IT administrator, you pretty much handle everything that tech touches. From servers and security to databases and GIS, it all finds its way to your desk eventually. Sometimes that means troubleshooting authentication issues; other times, it means refreshing the aerial imagery that keeps your maps grounded in reality.
Our district continues to grow, with new subdivisions and roads reshaping the landscape each year. Keeping our imagery current isn’t just about aesthetics, it’s essential for accurate planning, operational awareness, and public trust. This month, we received a new Nearmap imagery link, high-resolution aerial data that captured the latest developments in stunning detail. The link would expire in 60 days, which meant one thing: act fast.
The 60-Day Race Against Time
Imagery links often have short expiration windows, and once they close, the opportunity is gone. To move quickly, I used ArcMap, a familiar tool, to overwrite our existing imagery service. ArcMap still performs well for one-off service updates, even as we prepare to migrate to ArcGIS Pro for future releases under ArcGIS Enterprise 11.x.
We currently operate on ArcGIS Enterprise 11.4, which still supports ArcMap-published services but represents the last generation to do so.
Why the Update Matters
Accurate imagery is the visual foundation for every spatial decision. In fast-developing areas, outdated basemaps can mislead planners, cause delays in infrastructure mapping, and complicate asset tracking.
To optimize both performance and offline usability, we requested the Nearmap dataset in MrSID (Multi-resolution Seamless Image Database) format rather than a live WMS or API feed. MrSID provides advanced compression and multi-resolution storage, meaning one file can deliver high detail when zoomed in while remaining fast to load in the field. It is particularly well-suited for offline environments, where field crews using ArcGIS Field Maps can work without connectivity and sync edits later once online.
How It Was Done (The ArcMap Way)
The Nearmap imagery arrived as multiple .SID tiles covering the full district. After verifying the projection matched our standard NAD 1983 StatePlane California III (Feet) coordinate system, I used ArcMap’s Share As Service tool to overwrite the existing imagery service hosted in ArcGIS Server 11.4.
Workflow:
- Downloaded imagery within the 60-day window.
- Verified spatial reference consistency.
- Loaded rasters into ArcMap and checked alignment.
- Used the Share As Service tool to overwrite the existing service.
- Validated cache parameters (tile size, levels of detail, and format).
During the overwrite, users briefly saw gray tiles as ArcGIS Server cleared cache locks, temporary system holds that prevent cache files from being modified during active use. Once cleared, the cache reloaded and normal rendering resumed.
In older Enterprise versions, overwriting can delete the cache entirely, forcing a full rebuild that can take hours or days. Using ArcGIS Server’s Manage Map Server Cache Tiles tool, I reseeded only updated extents to minimize downtime.
That One Annoying Thing: The RDP 2GB Limit
Large file transfers via RDP can fail due to a 2GB clipboard limit, a legacy constraint from when Remote Desktop Protocol was built for small administrative operations, not multi-gigabyte imagery. Files exceeding this limit silently fail to copy, no error, no warning.
To bypass this, I used RDP drive redirection, which maps a local drive directly into the remote session. This allows you to move large datasets as if they were on the same network.
How to enable drive redirection:
- Open Remote Desktop Connection.
- Click Show Options → Local Resources → More… under Local Devices and Resources.
- Check the drive (e.g., C:) to make available.
- Connect, then open This PC on the server, you’ll see your local drive listed under Redirected drives and folders.
Alternative options include:
- SMB file sharing for on-prem transfers.
- Azure Files or OneDrive for hybrid or cloud-hosted environments.
Overwriting vs. Publishing New
- Overwriting keeps the same service name and endpoint, ensuring that maps and dashboards stay connected. The trade-off: brief downtime during cache rebuilds.
- Publishing new services provides a clean slate and allows testing, but requires updating all dependent maps and apps.
For routine updates, overwriting is the efficient choice. For schema or cache redesigns, publishing new is safer.
Caching in ArcGIS Enterprise 11.4
Caching remains one of the most resource-intensive parts of maintaining imagery services. While Enterprise 11.4 includes improved parallel seeding, cache rebuilding can still consume substantial resources for high-resolution imagery.
To optimize performance, we kept the cache schema intact and used Manage Map Server Cache Tiles to reseed only changed areas. This incremental approach avoids full cache rebuilds and allows administrators to prioritize updates by region.
Looking Ahead: Automating with ArcGIS Pro and Python
Although ArcMap served us well for this update, future updates will be automated using ArcGIS Pro 3.x and arcpy.mp, the Python module for managing maps, layers, and services in ArcGIS Pro projects.
This automation approach ensures consistency, reduces downtime, and minimizes manual errors.
Requirements:
- ArcGIS Pro 3.x or later installed.
- An existing
.aprxproject file with the target map. - A valid
.agsArcGIS Server connection file for publishing rights.
Example Script (with line numbers and inline comments):
01 import arcpy, os
02
03 # Define project and data paths
04 project_path = r"C:\GIS\ImageryUpdate.aprx"
05 new_data = r"C:\NewImagery"
06 old_data = r"C:\OldImagery"
07 server_conn = r"C:\ArcGISServer\connections\MyServer.ags"
08
09 # Open the ArcGIS Pro project
10 proj = arcpy.mp.ArcGISProject(project_path)
11 m = proj.listMaps("Imagery")[0]
12
13 # Confirm the imagery layer exists
14 layers = [lyr for lyr in m.listLayers() if lyr.name == "District_Imagery"]
15 if not layers:
16 raise Exception("Imagery layer not found in project.")
17
18 # Update data source paths
19 layers[0].updateConnectionProperties(old_data, new_data)
20
21 # Create and stage the service definition
22 sddraft = "Imagery.sddraft"
23 sd = "Imagery.sd"
24 arcpy.mp.CreateWebLayerSDDraft(m, sddraft, "District_Imagery", "ARCGIS_SERVER")
25 arcpy.StageService_server(sddraft, sd)
26
27 # Overwrite the existing service
28 arcpy.UploadServiceDefinition_server(sd, server_conn)
29 print("Imagery service successfully overwritten.")
This script validates the layer before overwriting, stages the .sd package, and deploys it automatically to the ArcGIS Server connection, ideal for scheduled updates.
The Old Tool Still Works
ArcGIS Pro may be the future, but ArcMap still delivers when speed and certainty matter most.
The new Nearmap imagery is now live, crisp, and accurate. As I zoomed in, I could see new houses built just last year, entire neighborhoods that didn’t exist in the previous imagery. It’s a reminder that maps are never static, they evolve with the communities they represent.
Call to Action
If you manage imagery in ArcGIS Enterprise 11.x, how do you handle updates and caching?
Have you automated your workflows with arcpy.mp, or are you still managing them manually?
And for those working with compressed imagery formats, MrSID, ECW, or GeoTIFF, how have they affected your performance and storage strategies?
Share your insights, especially around cache optimization and transitioning from ArcMap to ArcGIS Pro. Every organization has a unique approach, and those lessons often help others streamline their workflows.
For documentation and examples, see the Appendix below.