Aligning GRTS cells

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09-29-2015 03:11 PM
MatthewRice
New Contributor II

So I have 2 separate GRTS (Generalized Random Tesselation Stratified) for spatial sampling that I want to align but am having trouble even after projecting them to the same coordinate system (Projected: NAD_1983_Albers / Geographic: GCS_North_American_1983).

Any suggestions?

GRTS_Overlay.PNG

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4 Replies
DanPatterson_Retired
MVP Legendary Contributor

What were the geographic coordinate bounds for both files, prior to the projection? and what were the projection parameters you used for both

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MatthewRice
New Contributor II

Both are the custom projection below

NAD_1983_Albers

Authority: Custom

Projection: Albers

False_Easting: 0.0

False_Northing: 0.0

Central_Meridian: -100.0

Standard_Parallel_1: 55.0

Standard_Parallel_2: 65.0

Latitude_Of_Origin: 50.0

Linear Unit: Meter (1.0)

Geographic Coordinate System: GCS_North_American_1983

Angular Unit: Degree (0.0174532925199433)

Prime Meridian: Greenwich (0.0)

Datum: D_North_American_1983

  Spheroid: GRS_1980

    Semimajor Axis: 6378137.0

    Semiminor Axis: 6356752.314140356

    Inverse Flattening: 298.257222101

NAD_1983_Albers

Authority: Custom

Projection: Albers

False_Easting: 0.0

False_Northing: 0.0

Central_Meridian: -96.0

Standard_Parallel_1: 29.5

Standard_Parallel_2: 45.5

Latitude_Of_Origin: 23.0

Linear Unit: Meter (1.0)

Geographic Coordinate System: GCS_North_American_1983

Angular Unit: Degree (0.0174532925199433)

Prime Meridian: Greenwich (0.0)

Datum: D_North_American_1983

  Spheroid: GRS_1980

    Semimajor Axis: 6378137.0

    Semiminor Axis: 6356752.314140356

    Inverse Flattening: 298.257222101

GRTS_Overview.PNG

GRTS_Overview2.PNG

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DanPatterson_Retired
MVP Legendary Contributor

Wow...you central meridians are different and so are your standard parallels, no wonder they look funky. They are definitely not the same ... except for the first 2 lines ...  NAD_1983_Albers, Authority: Custom

They are both Custom but that is about it.

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MatthewRice
New Contributor II

I didn't know if I could correct the Canadian one, I end up redrawing the fishnet, the problem was that I wanted to extract the data from the original one into the new grid draw but since the polygons won't be aligned I wouldn't get matching results. I run into the problem below where the IDs get out of order.

Red is original (skewed)

Green is new grid draw trying Spatial Join to match polygons.

id_changes_by_percent_contained.png

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