Northland Photoscenery

[nzcoaster]

Hi Guys

I havent given up :-)

I know I'm not that active on the forums but I just logged in and thought to give an update on the situation with Photoscenery

In reference to questions asked from fellow simmers I will try to explain

At this stage I still am engaged in the photoscenery project for Northland and as Timmo
expressed in another thread there is alot of work to do for coastal and Island watermask and blends and have been trying to get a understanding of the best workflow for such a large data set as you can appreciate that up here there is a significant amount of inland harbors and tidal areas so I want to have a good blend of float plane landable water in these interesting areas. I like what I saw on Timmos thread about creating buffers etc and would be keen to know more.
It is a large data set and currently consists of about 15x 2.2gb geotiffs and about 3000 sq kilometers with a fair whack of that in the water and in order for me to work with these I neeed to divide the relevant tiles into 5x5 which gives me geotiffs about 250 mb which I can work with though these quickly gain size when you add alpha and blend mask.

If any one has tips for large scenery areas please let me know as it is abig undertaking

Other issues are as brought up licensing and data security
My current work for Whangarei District Council GIS has finished but still has a requirement of the photoscenery for the Council which they would quite like to see at the upcoming expo here. But due to this job having finished I have had to concentrate on finding New 2D 3D GIS Work up here. so time has been focused on this finding of $$

The Project for the Council is on a understanding of 2 products at the moment
1 Scenery for the Council of all Northland with only a water blend mask at the extreme edges of the scenery and land blend masks inland. This means that all the harbours are solid water but very nice photoscenery

2 As above except designed for Simmers who want to land on the water in harbours and see a wake instead of dust, this product is in my own time and subject to aproval from Whangarei GIS manager before I could release it. I do get on very well with him and really he only needs assurances of whether or not the stuff can be decompiled and used for commercial purposes, which is hard to give him those assurances given the nature of the sorts on the net, but I do think there are reasonable assurances I can give him . Anyone else hade this experience ??? with council owned data? let me know.

On the other hand my old boss recognizes that the data is really payed for by the ratepayers of Northland and is worth about $25,000 or more , and he would like to see people get something back which of course I heartedly agree with.
I know from talking with my old boss he would be quite happy for google earth to have the data except for his commercialconcerns.

So to sum all this up Guys and Girls

Yes I'm still working on this

Yip it sure does take time and energy

It is big and I need ideas and help from any one who has developed good methods for making watermasks blenmasks. I can use Globbal mapper 8 and have access to Arcview 3.2 with extensions and ArcView 9.1 without any extensions.

In the end if all goes well I would like to be able to offer Northland Scenery free or at a small cost to as many as want it. I would like to include autogen but that would be a secondary project.

Thanks for listening and I'll try to keep you in the loop

kind regards to all
Greg

[toprob]

Great to see that this is still viable, Greg.
Although I don't deal with images of that size, I do have some suggestions based on my experiences. (I only use LINZ images at 2.5m/px)
The largest images I tend to use are about 1.2GB. Editing these is difficult, that's for sure, I guess it depends on how much RAM you have. I find that editing goes at a good pace up to about 800MB on my 2GB system.
I find that a separate file for water and blend masks works best for me. I convert the original image to grayscale to reduce the file size, and the final mask file wants to be 8bit anyway. Working from grayscale is tricky though if the actual water isn't well-defined. I guess you would have better luck with that, though, starting with a much higher resolution image.
I'm glad you mentioned the 'retail' cost of the data. Certainly not possible to recoup these costs by selling scenery.
You have some nice tools there. I tend to use Micrografx Picture Publisher to mask. This is not available any more, but I find it has the best set of masking tools. The actual dividing line is masked using the 'paint-on-mask' tool. This is a variable-sized brush just like a paint-brush. I control the brush size on the fly with one hand on the keyboard, and draw the mask with the mouse in the other hand.
I think that it is possible to just use a paintbrush, though, if you start with a grayscale image. This means that you won't need a separate mask channel. Just paint the land white and the water black. The only trouble with this is that it is difficult to change the mask if you need to, because you don't have the original image.
Then once I have the water mask, I just feather it to make a simple water blend, then add a black-to-white ramp to the edges for an edge blend.

[Timmo]

Hi- This may have to be a quick post ats im on a training course (learning Python Scripting for ArcGIS)

My workflow is as follows:
The general idea of my scenery is that i wanted to totally avoid having to take it into a graphics package. I use polygons to define all of my areas of water (Landwatermask) and my blends (blendmask) by using buffers of my original water masks. I used ArcGIS 9.1 for all this work....im not sure Arc3.x would do it.

Ingredients:
Imagery. Im mostly using our region wide, 0.8m pixel imagery which is native NZMG but im using a map document that is reprojected to WGS84 (and handy feature of ArcGIS desktop). Ive defined the extent tiles for larger areas (i.e. Most of the Rotorua district that ive playing with) but these can only be used as approximations since Arc cant export an image with reference information based on a selected polygon (unless you Clip it ...as far as i know) So I just reposition/resize the window and export the three images (Image, Blend, Mask) for each tile and then pan the map to the next tile. I allow a fair bit of overlap to avoid problems with the resampler clipping the image to fit the lowest LOD. The exported image is a 32 bit full colour geotiff. For consistency i use the '_image' suffix to denote is an image (i.e. Motiti_image.tiff)

Polygon Mask This is used to define the areas of water on the image. In the case of my Islands scenery, I re-digitised the shoreline of each island because the data we had was 1:50 000 data and didnt line up properly to the photos. Even if it was higher quality, there would probably be differences due to image orthorectification errors....so i just re-did it. The 'LandWaterMask' image is simply a 8 bit greyscale image OF EXACTLY THE SAME AREA as the actual image. I use the '_mask' suffix to denote it is a mask (i.e. Motiti_mask.tiff)

Blend Mask This is used to blend areas of imagery into the default areas. In the case of my islands scenery i did a buffer of the shoreline: 10 or so concentric rings each of 10m and saved into a new shapefile. I then coloured these using a greyscale colour ramp so that the water areas on my imagery gradually blended back into the default water. I saved this image as 'Motiti_Blend.tiff' as a 8 bit, greyscale image OF EXACTLY THE SAME AREA

I found that if you slightly moved your map window between exporting the image or the mask or the blend, it wouldnt align the data (i.e. the resampler only seems to read the spatial reference information from the first image! ?)

Cheers

[Timmo]

I should add that the Quality/size of the images is defined when i export the images from arc (i.e. a glorified screen grab) It asks you to set the DPI of the exported image so by setting this higher the images are higher quality and vice versa (of course you cant get better than the source image)

The spatial resolution will be defined by a combination of DPI and the scale of map window. These variables arent changed when exporting the series of images (so therefore the spatial resolution wont change between tiles)

[nzcoaster]

Thanks guys

I really appreciate your reply s and methods and as soon as I get some spare time I'll be launching back into the project and trying your methods. I'm a bit snowed under the moment with problem solving stuff and a huge database reconstruction for a company thats a bit more than I should have taken on.

I'll be in touch as I can

Many thanks
Greg

[Kelburn]

hows it coming along at the moment?

[stubbie]

QUOTE (nzcoaster @ Mar 10 2007, 03:22 PM) <{POST_SNAPBACK}>

Thanks guys

I really appreciate your reply s and methods and as soon as I get some spare time I'll be launching back into the project and trying your methods. I'm a bit snowed under the moment with problem solving stuff and a huge database reconstruction for a company thats a bit more than I should have taken on.

I'll be in touch as I can

Many thanks
Greg

hi there any update on this project or have i missed something