AnsweredAssumed Answered

Raster mosaic datasets: Overview Quality control

Question asked by dhuhkosi on May 5, 2016
Latest reply on May 30, 2016 by pbecker-esristaff

Dear ESRI Support and GIS Users.

 

Can anyone help me with how best to get good quality overviews? I know this is a little subjective…my case:

 

I create the Raster Mosaic Dataset in a fGDB and add the following tifs to it.

 

200 tifs, each tif 20MB in size, all tifs fit together like squares on a chessboard

 

Each tif:

Number of bands: 3

Cell size 1.25 x 1.25

Format: TIFF

Source Type: Thematic

Pixel Type: unsigned integer

Pixel Depth: 8 bit

NoData Value 256,256,256

ColourMap: absent

Pyramids: absent

Compression: LWZ

 

TOOL PARAMETERS

 

DefineOverviews

Overview Tile Parameters

Pixel size: 1.25

Number of Levels: 12

Rows: 5120

Columns: 5120

Overview Sampling Factor: 2

 

Overview Image Parameters

Resampling Method: BILINEAR

Compression: LWZ

 

Calculate item visibility – take Default settings.

 

RESULTS

 

Scale 1:8000 –= viewing the original tif, not the overviews – quality good

Scale 1:8000 – 20000 = viewing the overviews – quality poor. I know this is a little subjective – but the image is quite
blurred, hard to read labels…

 

 

TESTED:

 

[1] I have tried changing the Number of Levels and Overview Sampling Factor

[2] I have tried changing the Resampling Method and Compression

 

Nothing seems to help.

 

QUESTIONS

 

[A] Is the problem in the original tifs? For example the source Type or Compression used?

[B] Is the problem in how I define the Overview Generation?

 

Feedback welcome and appreciated.

Outcomes