Google Mars HiRISE base images for Opportunity Options

[elakdawalla]

Because it has become a forum FAQ, I've created this sticky thread containing information on where to obtain new base images for Opportunity's traverse for Google Mars, and for discussion on creating new ones. I will continue to add links to new base image layers to this first post as they become available.

New users: Download this 4-MB kml file and open it in Google Earth
Then go to the last post in the Opportunity Route Map thread for the latest traverse map
You need to download the new KML file each time in order to follow Opportunity's peregrinations.

Google Mars comes with a color base image mosaic created from HRSC imagery. In addition, there is an inset full-resolution HiRISE image covering the area from the landing site at Eagle crater, through Victoria, up to the point between sol 2040 and 2041 (just west of Mackinac) where Opportunity drove off the map.

Unfortunately, this Victoria crater HiRISE layer included within Google Mars is not perfectly registered to the HRSC base map. As far as is known, there is nothing to be done about that. Both John Cody's image layers and Eduardo Tesheiner's traverse maps are aligned with the inset HiRISE layer included with Google Mars, NOT to the HRSC base map.

In June 2009 SFJCody posted a reduced-resolution mosaic of HiRISE tiles that cover the entire future traverse area including Endeavour's rim. I have made some small modifications to that map and have hosted it in a single file here (17 MB). Download the file, run Google Earth, select the Mars view, and File>Open the KMZ to view it.

In September 2009 SFJCody posted another HiRISE base image, this one at full resolution, covering the Western Route and reaching not quite all the way to Santa Maria. Here is a link to the kml file (4 MB). Here is a link to a zipped version if you'd prefer to have it locally (256 MB) and I also wrote a blog entry about it.

During the discussion below, in late 2010, I created a small tile that covers just the immediate area around Santa Maria. Here is a link to the kml file covering that region.

In February 2011 Eduardo Tesheiner provided another set of base images covering the area from Santa Maria to Endeavour's rim. Here is a link to the kml file. If you would like to work from a local copy, you can download this 75 MB zip file and unzip it to a folder on your drive, then open the file PSP_010341_1775_RED.kml within it.

All three base images can be loaded at once using this kml file (the same one that is linked to at the very top of this post).

[Tesheiner]

Bingo!



Thanks Walfy for finding the right tool! Map Tiler
Emily, I think the biggest problem to have the extended maps is solved but I still see an open point which is the transparency of the black areas outside the map-projected picture. The original 8k x 8k images should be available in PNG format with the transparency already set.

This post has been edited by Tesheiner: Sep 30 2010, 04:37 PM

[walfy]

Nice progress! I had a feeling you would propel this forward. I was able to set the black part of the images to transparency by first opening the image in Photoshop, then going to "Save for web & devices." In there you can choose the transparency to the black when you set it to save as a GIF. Not sure if it's the best way, but SFJCody's images were done similarly because they have the same very small transparency artifacts along their edges when you zoom way in.

To match the lighting of the new images with the old, maybe you could open the image of SFJCody's in photoshop, the one nearest Santa Maria, then increase the canvas size of the image large enough to place the new and slightly darker image with Santa Maria in it. Once they are in there side-by-side, adjust the curves settings on the Santa Maria image until it matches SFJCody's image. Then crop out SFJCody's image, then you have a color-matched Santa Maria image.

But personally, I don't think it's necessary to change the brightness levels of all the images. If you're going to do it for the first one, then you're going to have to do it for all of them! It's not a big deal for me if the end result has 2 large image overlays of different brightness side-by-side. It will save a lot of moil and toil to skip the step of matching the brightness levels.

Those are my two bits. OK, back to my job. Otherwise, I'd be tinkering with all this... maybe tonight.

[Tesheiner]

Nice progress! I had a feeling you would propel this forward. I was able to set the black part of the images to transparency by first opening the image in Photoshop, then going to "Save for web & devices." In there you can choose the transparency to the black when you set it to save as a GIF. Not sure if it's the best way, but SFJCody's images were done similarly because they have the same very small transparency artifacts along their edges when you zoom way in.

I have Serif Photoplus instead of Photoshop but AFAIK they have similar capabilities. GIF is probably not the best option because if you set black = transparency all dark areas *inside* the real image are also made transparent. Another option is to edit the picture, set/fill all the contour as transparent and save as PNG. Simple but ... it's too much for my computer; the image is too big.

[walfy]

...GIF is probably not the best option because if you set black = transparency all dark areas *inside* the real image are also made transparent. Another option is to edit the picture, set/fill all the contour as transparent and save as PNG. Simple but ... it's too much for my computer; the image is too big.

It's not a problem, as there are no pixels in the actual image of the surface area that are as black as the background pixels outside the image. I tested this using the "Magic Wand" selection tool in Photoshop, which you can set to select only pixels of the same color of an image. It only chose those pure black pixels outside in the background, nothing on Mars' surface area. One drawback of GIF image format is that it reduces the number of pixel types to just 256. The GIF still look identical to the non-GIF image, at least to my eye, but the thought of the color gamut reducing to just 256 colors sounds bad to me!

Your PNG suggestion sounds great, if I have time tonight I'll try it . My Mac can handle the large files.