Scale definitions

[Christian-Shom]

New definitions were agreed during Scale Sub-Group meeting 16 November 2021:

• Max. and Min. Display Scales definitions have been aligned with S-100 5.0.0.
• a new definition has been added for "Viewing scale".

[juanbreizh]

[test] seems ok for me !

[Christian-Shom]

Definitions have been aligned with S-100 5.0.0:
Maximum Display Scale: The maximum scale with which the data is displayed.
Minimum Display Scale: The minimum scale with which the data is displayed.

However, this will not be true in practice, as a S-101 dataset can be displayed:

• at a larger scale than the Max DS (with or without over scale indication);
• at a smaller scale than the Min DS (to a certain extent that is to be agreed), if no smaller scale dataset is available.

I haven't looked at other S-1XX PSs to see what is said.
I am of the opinion that definitions in the S-101PS should stick to how S-101 datasets are really displayed. But this would mean inconsistency with definitions in S-100...

[Christian-Shom]

Suggest to change the definitions to:

• Maximum Display Scale: The maximum scale with which the data is intended to be displayed.

• Minimum Display Scale: The minimum scale with which the data is intended to be displayed.

and report to the S-100WG to align with these definitions in all related standards (S-100, S-102, S-98, etc.).

[alvarosanuy]

Refer to AU comments in the S-101 PS 1.1.0 draft review:

• maxDScale – Optimum ratio between the level of detail and the accuracy of the information provided. It is the recommended maximum MSVS for the data coverage.

• minDScale – Recommended smallest MSVS for the data coverage due to an elevated possibility of data cluttering and reduced data clarity and readability.

[Christian-Shom]

The issue I see with Alvaro suggested definitions is that they are very different from the ones we find in S-100.
Couldn't we keep a very simple definition (consistent with S-100) and then add more guidance in the PS (clause 4.5) on what these scales are for a Data Coverage?

[Christian-Shom]

UKHO comments in the S-101 PS 1.1.0 draft review: "The ownness is on the data producer to determine the MaxDS."
Suggests:

• Maximum Display Scale: The maximum display scale with which the data producer had intended the data to be displayed.

[MikusRL]

I am sharing a comment on this topic as an observation, reading the comments as above.

I think that the S-100 v5.0.0 definitions are OK, as mentioned by Christian's comment on Jun 29, if looking form different angles and users of S-100 perspectives, including the needs for S-101 PS. I tend to agree that a good further explanation for encoders either in S-101 PS or in DCEG should detail out (or further refine/define) the definitions from S-100.

For example the explanation after the Maximum Display Scale generic S-100 definition could be then something along the lines of: " For the navigational ENC this is the largest scale the producer has designed the data to participate in portrayal generation for ECDIS display and data analysis and calculations within ENDS (Alarms and indications, maximum MSVS, etc). At the ENC product's compilation the Producer considers this scale as the best for optimum ratio between the level of detail and the accuracy of the data to be used for safe navigation within the area of coverage. "

And similarly the explanation after the Minimum Display Scale generic S-100 definition could be then something along the lines of: " For the navigational ENC this is the smallest scale the producer has designed the data to participate in portrayal generation for ECDIS display and data analysis and calculations within ENDS (Alarms and indications, maximum MSVS, etc). At the ENC product's compilation the Producer considers this scale as a threshold where the data become cluttered and unreadable from the portrayal perspective or become too detailed for any navigation related analysis and calculations in smaller scales for safe navigation within the area of coverage. "

The explanations do not contradict the generic defined definitions, and are more flexible for us to fine-tune than trying to fine-tune the generic definition of S-100 to fit better S-101 PS. The explanations also better lead S-101 PS users into the ECDIS and ENC application specifics, and can therefore be more practical and beneficial during implementation.

[alvarosanuy]

I think we all agree that it makes sense to have 2 levels of detail in the explanation of the terms (S100 vs PS/DCEG). They have to be consistent though.
Also critical is to manage the definitions among S-100 PS, particularly those expected to work together during the Route Monitoring phase of the navigation.
The AU definitions were prepared with the intent to facilitate the practical interpretation and use by compilers and mariners (e.g. if I zoom more than maxCS then my display becomes less accurate as detail has been omitted due to generalization. Features that exist may not be shown. Do not get close to things, etc, etc). I think that, although far from perfect, they help answer the 'so what'? question that those stakeholders may end up asking themselves when reading the definitions in S-100.
Also note that S-98 Annex C (C-1.2.1) does refer to both, max and min display scales as 'scales at which the ENC was designed to be displayed' ... Christian has used intended which is close but not the same.
Again, I think we need to provide more info on the 'so what?' in the PS and DCEG.

[Christian-Shom]

I suggest the following to move foward for ed 1.1.0:

• We validate definitions for Max and Min DS: "The Max/Min display scale at which the data was designed to be displayed.", and report to the S-100WG via the S-101PT.
• We agree adding additional guidance in the PS (to explain the portrayal/ECDIS aspects) and in the DCEG (but what? avoiding redundancies with the PS).
• We find a few volunteers to produce wording before 26th October.

[Christian-Shom]

Sub-Group meeting 2022-10-19 agreed on:

• Maximum Display Scale: "The maximum (largest) display scale with which the data is designed to be displayed."

• Minimum Display Scale: "The minimum (smallest) display scale with which the data is designed to be displayed."

• Additional guidance on Max and Min Display Scales needed in the PS. Volunteers: Christian, Alvaro and Jeff.

[JeffWootton]

Consider that this issue has been resolved in S-101 Edition 1.1.0. Close.