Raster resolution degraded when zoomed out

RichardThurau · ‎04-24-2015

Hi Community,

Our issue is when providing raster maps 1:100K (Digital Raster Graphics; DRGs) for field use, the maps are degraded in both viewing and printing.

In the attached example, the right side of the image maintains quality resolution when zoomed out. The left side shows how the image is degraded when zoomed out. We're assuming the problem is in the pyramid build, but there doesn't seem to be an acceptable solution available.

- We know that the right side image was created (pyramids built) in Arc 9.3. Pyramid files are .rrd.

- The left side image as created in Arc 10.x. Pyramid files appear to be .ovr

- Arc 9.3 used Erdas Imagine's method of pyramid creation.

- Imagine and Arc no longer like each other, so even if we built pyramids in current Imagine, Arc would require a rebuild.

ESRI has been unresponsive with any type of solution.

Has anyone else encountered this or similar? Even better, does anyone have a remedy?

Thanks for your thoughts or advice.

Rich

DanPatterson_Retired · ‎04-24-2015

too many ways to create pyramids the output formats... tell us what you used from the help file topics

from an overview of raster settings and the ovr format

plus others

HeatherFonda · ‎04-27-2015

Hello,

I am a co-worker of Richard's. We have tried multiple ways of creating the pyramids in 10.2.1 and 10.3 with no success. We primarily use the Build Pyramids tool to create 7 levels with Nearest Neighbor resampling and LZW compression. We have tried 6 and 8 levels as well and making sure the Raster Storage Environment Settings are the set to the same. The goal was to match the parameters of the tiffs with pyramids created in 9.3 or earlier because they will be used in a mosaic and image service.

The tiffs created in 9.3 and prior have good resolution at all scales while the ones with pyramids created in 10.0 or later are degraded at scales smaller than around 1:30,000. (Although really the tiffs from 9.3 are even crisper at larger scales too but the problem is more pronouced the more you zoom out.) Lines become dashed and text illegible. This does not work for our purposes.

The tiffs look great in other programs such as Illustrator, Photoshop and even Photo Viewer.

DanPatterson_Retired · ‎04-27-2015

This is a problem that should be investigated by Esri tech support...unfortunately we are not that. I recommend that you contact them, they will want your documentation and a set of test data I suspect. sorry I can't be of more assistance, but that will most likely be the suggested course of action.

YuriPotawsky · ‎04-28-2015

Heather,

Are you aware of what the Resampling method used during display is set to? In many circumstances with Digital Raster Graphics this will default to Nearest Neighbor which is optimized to render discrete datasets. Are the DRG's single-band datasets rendered with a colormap or 3-Band rendered in the RGB colorspace? Is there a way in which to obtain a sample of the 9.3 .TIF Raster Datasets?

Thanks

HeatherFonda · ‎04-28-2015

Yuri,

It is Nearest Neighbor. Although, I have tried the other options just to

see if there was an improvement. Either it looks the same or it is worse.

It is a 3-Band rendered in the RGB colorspace,

I can send some samples but is there a secured location for uploading them

to you?

Thanks

Heather Fonda

Geographer

Division of Resource Services (NOC)

Bureau of Land Management

Denver Federal Center, Bldg. 50

PO Box 25047

Denver, CO 80225

303-236-3549

EGIS Portal <https://egisportal.blm.doi.net/portal/home/index.html>, BLM's

Internal GeoSpatial Gateway

<https://blmspace.blm.doi.net/oc/intra/drs/Pages/GeoSpatialGateway.aspx>

MikeCusi · ‎04-28-2015

My work-around involves a lot of work but it works. If your rasters are in tiles, you will first create a full resolution mosaic. Then using this mosaic you will create your own set of "pyramids" by resampling your mosaic to the various scales you expect to use in the field. You would then set them up so that they display only at the scales you created them for. Every time you zoom in or out it will just be displaying the optimal rasters. Note that the full resolution mosaic should be displayed only when you are zoomed in at the larger scales.

HeatherFonda · ‎04-29-2015

Mike,

Thank you for your suggestion. I don't think it will work for this

particular project though. There are over 600 tiffs that cover the western

US and each one is about 370 mb uncompressed. Plus, a batch of them are

updated every couple of months so I would need to rebuild the resampled

scale levels to account for these updates.

Question: Could ArcMap be resampling in something other than Nearest

Neighbor even though that is what I am telling it to do? I ask because even

if I remove the pyramids completely, the tiff still has degraded resolution

unless it is viewed at its exact resolution scale usually 1:22,677.

Otherwise, it looks like it is using Cubic or Bilinear.

Thank you,

Heather Fonda

Geographer

Division of Resource Services (NOC)

Bureau of Land Management

Denver Federal Center, Bldg. 50

PO Box 25047

Denver, CO 80225

303-236-3549

EGIS Portal <https://egisportal.blm.doi.net/portal/home/index.html>, BLM's

Internal GeoSpatial Gateway

<https://blmspace.blm.doi.net/oc/intra/drs/Pages/GeoSpatialGateway.aspx>

MikeCusi · ‎04-29-2015

Hi Heather,

NN is the default resampling as it is the least processing intensive. If it was cubic or bilinear it should look better than NN. So I would expect that NN will be used if no resampling method is specified.

As there seems to be no solution yet from ESRI, we are left only with workarounds which is always painful . If the only other alternative is to use the degraded image, I am sure we or maybe someone else can work out a better way of accomplishing what I suggested earlier.

You can resample each (of the 600) tiffs to the pixel sizes you would like to use for your "pyramids" and then mosaic them all together (or into predetermined tiles if it is just too big). This can all be batched so it will just take some time but you would at least get a decent looking map.

What do you use for serving/accessing the images in the field? Is it an online/mobile one or is it all on a local (laptop/portable) drives?

Cheers,

Mike