Concepts of Orthophoto and Ortho Mosaic and it's work flow on INPHO PDF

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CONCEPTS OF ORTHO PHOTO AND ORTHO MOSAIC AND IT’S PRODUCTION PROCESS ON INPHO. By :T.Yetmgeta Addis Abeba Oct. 2015 CONTENTS OBJECTIVES General  To discus the concepts of orthophoto and ortho mosaic, and highlight its production on INPHO. Specific o CONCEPTS OF ORTHOPHOTO Dictionary mining  Ortho=...

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CONCEPTS OF ORTHO PHOTO AND ORTHO MOSAIC AND IT’S PRODUCTION PROCESS ON INPHO.

By :T.Yetmgeta

Addis Abeba Oct. 2015

CONTENTS

OBJECTIVES General  To discus the concepts of orthophoto and ortho mosaic, and highlight its production on INPHO. Specific o

CONCEPTS OF ORTHOPHOTO Dictionary mining  Ortho= corrected, right  Orthophoto= corrected photo.  An orthophoto is a photograph derived from a conventional perspective photograph so that image displacements caused by camera tilt and relief of terrain are removed  Is geometrically equivalent to conventional line maps.

CHARACTERISTICS of ORTHOPHOTO     

It have uniform scales in different terrain relief, no or less distortion. have true distance, angel and area. It has orthographic view. Areal photo with no occluded area. Original Image

Orthopotho

THE DIFFERENCE BETWEEN ORTHO AND LINE MAP. Ortho photo

Line map

It is the real image of the object or area.

It is the representation of the area or object in lines or symbols.

It is easily understandable by lay people

It requires cartographic or engineering back ground to understand.

Contour lines should super imposed to signify the actual elevation of the area.

Naturally it is like that!

Un able to visualize under ground utility lines.

Good on this.

WHY ORTHOPHOTO PRODUCTION? 

An areal photograph has distortion and displacement.  Where as even a perfectly vertical air photo is a perspective view from the central point. Distortion and Displacement in AP. o Distortion:- Shift in the location of an object that changes the perspective characteristics of the photo. o Displacement:- shift in the location of an object in a photo that does not change the perspective characteristics of the photo (The fiducial distance between an object's image and it's true plan position which is caused by change in elevation) .

MEJOR DISTORTION AND DISPLACEMENT 1

Lens distortion

2

Relief displacement

3

Camera tilt

• •

Lens Distortion Ellipsoidal shape of lenses causes radial distortion. It can be calibrated using lens parameters. Distorted

Corrected

• •

Relief Displacement The shift of an image from its theoretical datum location. Caused by the object’s relief. Ortophoto

Vertical photo (same nominal scale as the ortho)

Oblique view

Camera Tilt • When the optical axis is tilted from the vertical.  Omega(ώ) ◦ ◦

Rotation about the X axis Caused by roll X

Y



CONT… Phi ( ) ◦ ◦ ◦

Rotation about the Y axis Caused by pitch Strong head winds tend to cause pitch X

Y



…CONT Kappa(K) ◦ ◦ ◦

Rotation about the Z axis Caused by yaw strong side wind bring yaw.

Orthophoto production on  Ortho Master:-is INPHO product for Orthophoto production. 

Ortho Master:- effectively eliminates the relief displacements by intersecting the given 3D object data with the basic DTM, and utilizing advanced computation algorithms for generating true Orthophoto. What Ortho Master do in back ground for Orthophoto production?

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Camera calibration= To remove lens distortion

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Areal triangulation = To avoid camera tilt.

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An adjusted DTM = To adjust the relief displacement.

RESAMPLING METHODS (ALGORITHM) 1. Nearest neighbor assignment

The input image cell

nearest neighbour assignment will determine the location of the closest cell centre on the input raster and assign the value of that cell to the cell on the output raster. The value 2 in the input raster will always be the value 2 in the output raster; it will never be 2.2 or 2.3.

2. Bilinear interpolation Bilinear interpolation uses the value of the four nearest input cell centers to determine the value on the output raster. The new value for the output cell is a weighted average of these four values, adjusted to account for their distance from the center of the output cell.

The corrected image cell



…Cont 3. Cubic convolution

Cubic convolution is similar to bilinear interpolation except that the weighted average is calculated from the 16 nearest input cell centers and their values. In the cubic interpolation, the 16 cell centers from the input raster that are closest to the cell center for the output processing cell will be weighed based on distance, then averaged.

Getting Started  The program is started by starting the Applications Master, selecting or defining an Inpho project file and then selecting the Menu “Products > OrthoMaster” or pressing the corresponding icon button. 1.

1.2.

Ortho Master GUI

The main window of the Ortho master GUI contains three parts. o

Main menu

o

Main tool bar

o

Map window

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Work flow of Ortho Master Start the Applications Master Open an Inpho project file if not already done with the start of Ortho Master Generate surface model in DTM Toolkit Continue with Orthophoto Generation Import height model Import or automatically generate ortho-areas Start processing button a. Set processing options b. Press OK to start the computation of Orthophotos.

ORTHO MOSAIC

DEFNETION 

General Mosaic is the art of creating images with an assemblage of small pieces of colored glass, stone, or other materials.

Photogrammetric

OrthoMosaicking:- is the process of taking two or more overlapping ortho photos or images and "stitching" them together into a single Mosaic image, where the color shades and light reflections (from sun) has been balanced on entire area of the mosaic.

An Ortho mosaic is prepared if a single photo does not contain an extensive enough coverage, and/or if it cannot be enlarged to the required scale.

KINDS OF MOSAIC I.

II.

III.

Controlled:- It is prepared from photographs which have been rectified. Uncontrolled Mosaic:- it is prepared by simply matching the details of adjacent photos. There is no ground control, and vertical photographs which have not been rectified or rationed are used. Uncontrolled mosaics are more easily and quickly prepared than controlled mosaics. Semi controlled mosaics:- It is prepared by using ground control points but using photos that have not been rectified . It compromise between economy and accuracy.

…CONT

Simple mosaic:-

Often have tone missmatch.Usefull for visualazation of target area.The mosaic un even.

Seamless mosaic፡-

is a radiometrically and geometrically continuous series of orthoimages.

WHAT IS SEAM LINE? It is a polygon that defines the mosaic boundary of the raster data set used in an image service.  Seam lines are a collection of polygons with images associated with each region of the output mosaic.  Creating a mosaic produces seam lines that can be modified to control the appearance of the final mosaic product. o

USES OF ORTHO MOSAIC 1

Land use planning.

2

To study geological features.

3

It is easy to understand.

4

Large area can be prepared in much laser time.

ORTHO MOSAIC PRODUCTION

ON

(ORTHO VISTA)

Introduction Ortho vista is standalone application on INPHO. OrthoVista is a powerful software product that improves the quality, utility and value of ortho-rectified, digital image mosaics by performing a series of radiometric adjustments designed to match color and intensity across component images and producing seamless image mosaics. Multiple orthophotos are combined into one seamless, color balanced and geometrically perfect ortho mosaic. Large blocks of thousands of ortho photos can be processed without any subdivision.

GETTING STARTED 1. just double-click on the Ortho Vista icon to start the application.

Main window OrthoVista provides a number of tools that controls the way in which your imagery is displayed in the main window.

Main Window

Project Dialog Box

2. Load Project 

Select Add a whole directory from the menu bar… >format *.ipdformat o To see the image or to make it usable select all and press “A” then give the path of ortho photo. Change the image path

Set selected image as active

3. Color balance  Before starting mosaic we can adjust full image color a little bit here in ortho vista. Colorpicker Radiometrix editor





The Radiometrix Editor allows changing interactively the histogram, color, saturation, intensity, contrast of images before or after OrthoVista processing. The color picker allows checking the color of a certain pixel or the mean color of a selected area.

Cont… 4. Processing Select Begin Processing from the menu bar to specify the parameters for image processing.

Optional at this level.



SEAM EDITING

At this stage we have left one more thing with another INPHO application,that is ortho vista seam editor.  The Seam Editor is an add-on to OrthoVista, which enables as to define seam polygons manually. It is intended to be used in urban and continuously large areas. Where the automatic approach of OrthoVista may produce a non-desired result. The seam line editing is done by defining new seam line polygons that will replace the current seam lines. Get started Step 1 Launch the OrthoVista Seam Editor Step 2 Select Open Project and select the automatically generated *.ipd file from the processing. This file is located on the OrthoVista output directory.

 

Cont…

Step 3 Use the Set the selected images to active functionality in the Main window or the Project Dialog to deactivate edited images.  Step 4 Check the mosaics for situations that should be modified.  Step 5 Defining a new polygon to modify the mosaic. or Ctr+N or N o Step 6 Digitize the new seam line with the left mouse button as shown on the left with points 1 to 4.

…Cont   

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Fixing the Mosaic modifications with OrthoVista To fix the modifications defined with The Seam Editor you have to run OrthoVista. Step 1 Start OrthoVista and load only the orthophotos Step 2 Load the Tile Definition used for the generation of the mosaics Step 3 Select the tiles (mosaic areas), which you want to generate once more with the help of the modifications defined in The Seam Editor. Step 4 Open the Processing window Step 5 Select the same Metadata directory as used in The Seam Editor Step 6 Select “Seam Applicator” as mosaicking method and check the optional feathering parameters.

Step 7 Start Processing

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Conclusion Ortho photo

Seam editing

Ortho mosaic

Art…Science…Technology

Radiometrix, Color & Seam editing…

Resampling methods, Areal photograph Parameters…

Software(INPHO), Hard ware…

PHOTOGRAMETRY

REFERENCES 

Braun, J., 2003. Aspects on True-Orthophoto Production. Proceedings, 49th Photogrammetric Week, pp. 205-214. Stuttgart, Germany.  Trimble, 2014. OrthoMaster Software Manual for OrthoMaster Version 6.0, Trimble Germany.  Pauler Wolf,1983. Elements of Photogrammetry,Mc GrawHill Book Company,New York.  T.Schenk,2005. Introduction to photogrametry, Ohio State University,Ohao,USA.  Wilfried Linder,2009. Digital Photogrammetry. Springer, Heidelberg.Germany.

THANCK YOU...