[Civil 3D 2026.2] AeccEnhancedSpiralSampling

[Wojtek_Garczewski]

Hi All,

Civil 3D 2026.2 Update brings multiple improvements across drainage tools, Feature Lines, Dynamo, HRA, and alignment workflows.

If you work with alignments, try the adaptive mode and share your feedback.

New system variable: AeccEnhancedSpiralSampling
where:

• 0 – legacy
• 1 – adaptive, higher-accuracy spiral display

The adaptive method enhances the graphical representation of spirals, yielding a more accurate spiral display. (This is only related to spiral display representation accuracy, not underlying calculation logic.)

I'd love to hear about the performance and display accuracy improvements you've seen! Thanks!

[Cadguru42]

We are holding off installing C3D 2026.2 and ACAD 2026.1.1 until we get some answers regarding the Sheet Set Manager changes on ACC. Autodesk provided no documentation on how the "new" SSM affects DSTs. Can one user use the newest SSM while another uses "legacy" SSM on ACC? If the DST on ACC is edited by the new version, can the older versions still work on it? Can SSM4W still work on a DST at the same time as someone with the new SSM? Do C3D's viewframes now work properly on a DST that's stored on ACC?

https://forums.autodesk.com/t5/acc-general-discussion-forum/acad-2026-1-1-update-ssm-and-acc/td-p/13...

[KittyShen_Civil3D]

Hi @Cadguru42 ，

Thanks for the reply.
We've contacted ACAD team to request them to provide accurate answers to your questions along with official documentation in this topic.
While we wait for the response, from C3D team, we can confirm if you only install C3D 26.2, the workflow will remain unchanged for SSM.

The only difference you might notice is that the support file location has been removed from SSM4W (this has nothing to do with ACAD 26.1.1 and C3D 26.2, it's just an update for SSM4W).
Here’s the FAQ from the ACAD team that outlines the recommended solution: https://help.autodesk.com/view/ACD/2026/ENU/?guid=GUID-EB31E0D9-8F63-4556-9086-C30389CD9AA1

AutoCAD 2023-based through AutoCAD 2026-based Applications

Connected Support Files for cloud-based sheet sets must be set up from AutoCAD Web.

1. Log in to AutoCAD Web at web.autocad.com.
2. In the pane on the left, do one of the following:
   • If Autodesk Docs is listed, continue to the next step.
   • If Autodesk Docs is not listed, click Add Storage Source and then click Add adjacent to Autodesk Docs. In the Connect Autodesk Docs Projects dialog box, select the projects to connect and click Done.
3. If the project you want to work with isn't listed under Autodesk Docs, click Connect Projects. In the Connect Autodesk Docs Projects dialog box, select the projects to connect and click Done.
4. In the main area, click Manage Support Files to configure the support files for the project.
5. In the Support Files dialog box, add the support files used by the drawings and sheet sets in the project.
6. Click Done.

I understand this doesn’t fully resolve your problems, but I hope it helps eliminate your concerns and makes it easier for you to start exploring the other great features C3D 26.2 offers.

We’d love to see you take advantage of the latest updates and explore all the improvements we’ve introduced to make your experience better.

Thank you so much for your continued support and understanding!