S57 driver fails to apply update to lnam_refs correctly

[boatbeacon]

We are using the GDAL OGR S57 driver to extract data from the UKHO ENC data sets. We came across a bug with the extracted data ( a lighthouse with lights not attached) and reported it to the UKHO. They carried out a thorough investigation and narrowed it down to a bug in the OGR S-57 handling of updates. Specifically OGR S57 was applying the update correctly to remove the light objects (4 of them) and add 4 new light objects but it was failing to update the lnam_refs field of the lighthouse (a LNDMRK object) with the lnams of the new light objects. I have attached the feedback from the IC-ENC team below. I have the GB301478 data set available for reproducing the bug with, please contact me for a copy.

Feedback from IC-ENC:- Base cell GB301478: Creates the LNDMARK object and sets up the master-slave association with the four LIGHTS objects you noted GB301478 update2: Creates 4 more LIGHTS objects, deletes the original slave objects then overwrites the feature-feature pointers with the new LIGHTS created in the update. The reason that you cannot find the slave objects and have 4 co-located lights is because the OGR tools are wrongly processing update 2. They are reporting the original slave objects rather than the new ones. The data below shows a summary of the actions for update 2 followed by an XML encoding of the ISO8211 of update2 where you can see the modification of the feature-feature links.

R1[154b-1795] DSID DSSI 
R2[214b-1949] FRID Add  100/48775  LIGHTS FOID [540/620599488/5]  ATTF FSPT 
R3[210b-2163] FRID Add  100/48776  LIGHTS FOID [540/2147483647/6]  ATTF FSPT 
R4[210b-2373] FRID Add  100/48777  LIGHTS FOID [540/1546091932/7]  ATTF FSPT 
R5[210b-2583] FRID Add  100/48774  LIGHTS FOID [540/2147483647/4]  ATTF FSPT 
R6[55b-2793] FRID Del  100/2443  LIGHTS 
R7[55b-2848] FRID Del  100/2444  LIGHTS 
R8[55b-2903] FRID Del  100/2445  LIGHTS 
R9[55b-2958] FRID Del  100/2446  LIGHTS 
R10[137b-3013] FRID Mod  100/2429  LNDMRK FOID [540/2147483647/2508]  FFPC Mod  FFPT
 
<FRID>
    <RCNM>100</RCNM>
    <RCID>2429</RCID>
    <PRIM>1</PRIM>
    <GRUP>2</GRUP>
    <OBJL>74 [LNDMRK] </OBJL>
    <RVER>2</RVER>
    <RUIN>3</RUIN>
</FRID>
<FOID>
    <AGEN>540</AGEN>
    <FIDN>2147483647</FIDN>
    <FIDS>2508</FIDS>
</FOID>
<FFPC>
    <FFUI>3</FFUI>
    <FFIX>1</FFIX>
    <NFPT>4</NFPT>
</FFPC>
<FFPT>
    <LNAM>1C02D88B92C00400</LNAM>
    <RIND>2</RIND>
    <COMT></COMT>
    <LNAM>1C02C098FD240500</LNAM>
    <RIND>2</RIND>
    <COMT></COMT>
    <LNAM>1C02023C9FA50600</LNAM>
    <RIND>2</RIND>
    <COMT></COMT>
    <LNAM>1C029C7D275C0700</LNAM>
    <RIND>2</RIND>
    <COMT></COMT>
</FFPT>

[boatbeacon]

Data set to reproduce the problem

[boatbeacon]

Additional info about the object ID's

The unique S57 object id (lnam) for the lighthouse is 021CC3AEF58409CC and it is classified as a LNDMRK. The Lighthouse claims the following 4 attached objects (lnam_refs). (4:021C082CC0350827,021C0EEA97440828,021CFA43ED4C0829,021C94CCDBD6082A)

Here is the command I used to find what objects the lighthouse had attached

"ogrinfo -al GB301478/2/0/GB301478.000 |grep 021C082CC0350827"

None of these objects appear in the ogrinfo summary of the chart data for GB301478.

There are 4 unattached lights at the same position in GB301478 but their IDs are:-

021CC0928BD80004 (white light) and 021CA59F3C020005, 021CA59F3C020006, 021CA59F3C020007 (red lights)