Fabric COGO and Adjustments

NickN

I'm looking for some clarification with regards to spatial adjustments in the fabric. We model tax and lot parcels separately, but in most cases these are identical. We didn't have COGO on the data we migrated so are backfilling this as time permits and I want to optimize how we do this.

My understanding is that the adjustment uses COGO to calculate adjustment vectors of the fabric points. In the case of a tax parcel and lot parcel being identical, the fabric points will be shared between the two sets of lines, correct? Are lines without COGO ignored in the adjustment calculations, but still affected by the adjustment when applied?

If the answer to both of those is yes, then we should be able to only backfill COGO on the Lot lines correct? When an adjustment is run and points moved, since the points are shared all lines shared between points are adjusted, even the ones without COGO.

TimHodson

Hi Nick, yes you have answered your own questions correctly.

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@NickN wrote:

My understanding is that the adjustment uses COGO to calculate adjustment vectors of the fabric points. In the case of a tax parcel and lot parcel being identical, the fabric points will be shared between the two sets of lines, correct?

Yes. This would be what we'd expect to see. Sometimes you need to use the merge points tool when there happen to be exactly overlapping stacked points, or very close points that really should be a single point to represent a single shared corner.

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@NickN wrote:

Are lines without COGO ignored in the adjustment calculations, but still affected by the adjustment when applied?

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Yes.

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@NickN wrote:

...we should be able to only backfill COGO on the Lot lines correct? When an adjustment is run and points moved, since the points are shared all lines shared between points are adjusted, even the ones without COGO.

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Yes.

A general tip on running the least squares; note that you can also select the lines that you want to process in the least squares. Selecting the parcel polygons does work to include the boundary lines for the parcel, but it will not include any connection lines that are attached to the parcel. You need to select those connection lines as well. For this reason I personally like to simply work with the lines (parcel lines and connection lines), and directly select those lines to be processed. It's a bit less ambiguous about what lines are going to be used. As you note, if the line has no COGO, then even if it's selected it will not be "seen" by the adjustment.

-Tim