topic Re: Output feature shift from input data after Dissolving in Data Management Questions

Output feature shift from input data after Dissolving

MuhammedThouseef_MT — Thu, 01 Dec 2016 10:59:25 GMT

Hi All,

I have line feature class with different lines. When I am performing Dissolve operation, the generated output feature class (Same geodatabase & same coordinate system) showing a minute spatial difference from the input features. But I want to get the output without changing the location. I'm here with attaching the input and out put screen sots for your review. Please help me to solve this issue.

Re: Output feature shift from input data after Dissolving

NeilAyres — Thu, 01 Dec 2016 11:10:50 GMT

The usual questions here...

How small is the shift you illustrated?

What is the coordinate system? What type of db? What version?

Re: Output feature shift from input data after Dissolving

MuhammedThouseef_MT — Thu, 01 Dec 2016 11:15:07 GMT

Hi Neil,

Shift is very minute :0.000161 Feet

Projected Coordinate system:WGS_1984_Web_Mercator_Auxiliary_Sphere

File geodatabase, Feature class (ArcGIS Desktop 10.4.1)

Re: Output feature shift from input data after Dissolving

NeilAyres — Thu, 01 Dec 2016 11:21:38 GMT

I thought that Web Merc was a mteres based system, not feet.

But either way, that shift is very tiny, about 0.05mm.

You are probably hitting the limits of numeric resolution there.

Just zoom out a bit and ignore it.

Re: Output feature shift from input data after Dissolving

ChrisDonohue__GISP — Thu, 01 Dec 2016 16:14:51 GMT

I agree with Neil Ayres in that the shift is not of any major consequence and is likely at the limits of the software to resolve.

Note that if you are looking at the linework at a scale of less than 1:1 in ArcMap that what is seen is often a visual artifact. ESRI Tech support has confirmed that below 1:1 there can be visual results shown that are not representative of the data.

Strangeness - gaps unintentionally created while editing

One way to check if the depicted shift is of any consequence is to evaluate it against the XY Tolerance setting for the data. If the shift is below the tolerance, then the feature are considered coincident even though they seem to be off by a small amount.

ArcGIS Help (10.2, 10.2.1, and 10.2.2) (scroll down to Tolerance section)

Tolerance\resolution concept, (GeoNet discussion on XY Tolerance and Resolution)

Chris Donohue, GISP