Creation of 3D images from HRPT Data.

Its all fairly straightforward - but there are a quite a number of steps and pitfalls to avoid.

Ed Murashie wrote it up initially in 2003 and then Gerard Kruger in GEO Q #11- Sept 2006.

You need:

HRPT images from

NOAA CLASS Archive

Metop Manager

AVHRR Manager both from David Taylor

Software

Registered versions of David Taylor’s

HRPT Reader

GroundMap.

3DEM (free)

Digital Elevation Models

DEM - Globe Tiles (I've used the Mars MOLA tiles as well)

(That's the best part of 300MB compressed but its all free.)

Processing:

Load HRPT file into HRPT Reader. Chose a region which has plently of relief and is cloud free. Ensure overlay lines up accurately with image and then switch off overlay.

I don’t do any additional processing, leaving bright adjust at zero and Gamma at 1.0.

From file menu - 'save displayed image'.

This ensures there is no correction of the image and location data is saved as a .lcn file. (You can then reprocess the data in an imaging processing software - don't resize. However, I do it at the end.)

Open Groundmap. File Menu – ‘open location data’ – this assumes you haven’t used the software before. If you have, - ‘open mapping list’ first. This is created when you open your first .lcn file.

Options Menu. Output size – temporarily chose 800x600 or similar.

Location – user

Map Projection – I use Cylindrical equidistant (zoomed)

Setup

General – tick ‘use my map settings’ – chose Meridian and Parallel to suit your image – I initially go for Lon Span ‘10’ and Lat span ‘8’. This can be adjusted once you have a remapped image – ensuring it covers the area you want.

To find the area I use Fred van den Bosch’s POVIM AreaFinder

Overlay – you don’t want any overlay

Mapping – leave alone

Click ‘OK’

Now go back to ‘output size’ and chose ‘Giant – 3600 x 2700’.

Then – File Menu ‘save image’ – the default is ‘remapped’ but save it as something more memorable and default type is a bitmap ‘*.bmp’. This will be a rather large file.

Go to View menu – ‘Information’ and note Long and Lat details.

Now comes the really clever bit.

Open 3DEM

File Menu – ‘Load Terrain Model’

Check GLOBE Tile button and click ‘OK’

In ‘Coordinate selection either use sliders or crosshairs on map to select the centre of your image (detail given above) – ensure that width degrees is the same as the width (or larger) as your image. This should direct you to your Globe files and the header in the window gives the name of the tile you need.

Operation Menu – ‘F4 Apply/Remove Map Overlay’ – select ‘NO’ in popup message.

In ‘Apply Map Overlay’ popup click ‘Load’ – choose image and open it.

Click on ‘Geo Reference’ button and a new small window appears. You will see a blue cross in the upper right and a red cross in the lower left. Using scroll sliders go to top right of image. Click as close to the corner as you can – the blue cross hair should appear. Go to bottom left of image click again and the red cross should appear.

Next fill in the data boxes in the window as appropriate. You have to highlight each box – using tab to move boxes dosen’t work.

Click ‘OK’

You will now have your image overlying the 3D topography.

Within the image is a black square with a notch which can be positioned to size and view to suit.

Operation Menu – ‘F2 3D scene’

A ‘Terrain Projection Parameters’ opens.

One can experiment later, but for now try the following.

Legend – type in a name

Color

Size – 1024 x 768

Observer’s Altitude ( used when terrain Position is ‘background’)

Terrain Illumination – where was the sun when image acquired?

Terrain Vert Mag – this is down to personal preference – less than 500% rarely works – try 750%

Terrain Position – use ‘Foreground’, experiment with background later.

Terrain Resolution – tick Max – though it doesn’t seem to make a great deal of difference.

Terrain Type – chose most appropriate. If choosing Island/Ocean you may need to fiddle with the sea level to avoid presence of horizontal lines.

(All these options are there to be played with).

Finally click on ‘OK’.

From the image you have two menu choices – ‘Operation’ allows you to change some aspects of the 3D image and ‘File’.

Given this method of working the alignment between terrain model and satellite image should be reasonable.

If not go to Operation menu – ‘F5 Adjust Overlay’ and nudge and stretch until alignment perfect. Take your time about this. (It may be easier to go back to ‘Overhead view’ and adjust there.)

You can also adjust the viewing angle from ‘Operation Menu’ - ‘F6 Change Position’

‘Operation’ allows you to change other aspects of the 3D image.

In ‘File’ you have various ‘save’ options.

I then import the final image into ‘PhotoShop’ and adjust to suit.

Flyby – this is truly brilliant. I've posted an example here of a trip up the Kamchatka Peninsula .wmv file [689KB]

Go Back to initial ‘Overhead View’

Operation Menu – ‘View Flyby’

I still need to update this bit (5th Feb 2016

Alan

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