creating mosaics

[SLouq]

I am creating raster datasets out of imagery tiles and have a question about why some of the tiles won't display when zoomed out but does display when zoomed in.

Does this have to do with building overviews?

[EdMorris · Accepted solution]

Hi

If you are working wtih a geodatabase mosaic dataset then the answer is yes!

You are recommended to build overviews using the Build Overviews tool. This is because a geodatabase mosaic dataset has a default display value of 20 tiles.... if you try and display 21 tiles then one tile will not display..... so build your overviews (and pyramids for fast display when you want to view tiles before overviews kick in).

Hope this helps

many thanks ed

[SLouq]

Perfect! 

Thanks for the response

[EdMorris · Accepted solution]

A pleasure. Glad I could help

[SLouq]

I have like over a thousand different imagery tiles which I am creating Raster datasets from using the Mosaic to New Raster processing tool. Then I will build my Overviews on each Raster dataset and then create my Mosaic out of the raster datasets. 

[EdMorris · Accepted solution]

So what I proposed is for creating a Geodatabase Mosaic Dataset. A Geodatabase Mosaic Dataset references the tiles and treats them as a single object - think of it as an image catalog and are the recommended way of managing large volumes of imagery, which I think you have. Have a look here at Geodatabase Mosaic Datasets:

https://pro.arcgis.com/en/pro-app/3.1/help/data/imagery/mosaic-datasets.htm

I think what you want to do is create a different type of mosaic dataset - in which you will create a single raster tile in which all of the inputs are blended into that single tile which can be achieved by the Mosaic To New Raster geoprocessing tool. Building overviews will not work for this type of mosaic dataset - it will only work with Geodatabase Mosaic Datasets.

I would recommend you look at creating a Geodatabase Mosaic Dataset.

If this is not an option then I would use the Mosaic To New Raster geoprocessing tool. But note there are many things to take into account which might affect your output e.g. input raster properties (do they have colour maps? is the bit depth the same?...), the output raster dataset can be stored as many different file types (this could account for your missing tiles....; pixel type / bit depth.... there are many parameters which could cause the issue.

I would recommend that if you go down this route then mosaic 2 or 3 tiles to begin with to make sure that  the mosaic works, to make sure that the mosaic tile is created properly, it displays properly with no missing tiles.

Remember to build statistics and Pyramids on your output mosaic.

If this issue still persists then I would open a support call with your distributor. I suspect they will ask for:

- Software version

- A description of the issue and  an example workflow

- Some sample data

Let me know how you get on. I'm not sure what more i can offer after this....

Many thanks ed

[SLouq]

Thanks for your input on this.

I have done this twice before in 2018 and 2021 when we had flyovers and I had the same issue then. But eventually got those mosaics to display right. I just needed a refresher on what is going on since it's been 3 years. 

[DanPatterson · Accepted solution]

marking this as Accepted as Solution

if you have no real issue, since Ed has covered all that could be.