Conceptual problem?
I need some advice. How would you deal with this?:
"StereoMapper actually is the digital version of stereoplotter, taking topographic features from air photos. What it differs is its medium. On the hand, Aerial Photogrammetry extracts such kind of features directly from aircraft.
In general, StereoMapper is more convenient because we cannot always employ aircraft to film a region. Instead, we only need sit in front of computer and digitize the features we are longing for. It implies we can produce a topographic map whether it is stormy and sunny.
Also, the StereoMapper allows us to examine features very closely (to zoom in and out) so that we can collect and process image quite accurately. In contrast, aerial photos give us only an overview of the region although its quality is not bad. Its focus is fixed so that we cannot see its details accurately.
The most important thing is once we get aerial photos we have to do plainmetric mapping ourselves including radial triangulation and resection. This involves accurate hand and patient in order to map some features for only a region for a considerable time. Even mosaics and orthoimages, which are also photogrammetric products, need complex mathematical model to rectify photos and maintain their geometric relationship. But those vigorous calculation and photo rectification are absent in StereoMapper with just digitizing features that make up a topographic map.
Sometimes, it is not so advantageous to use stereo photogrammetry as features and sites change frequently because of new construction site and building projects. These change the landscape of a region. So we need to have aerial photos to tell us how change has been undertaken e.g. the effects of new buildings/roads upon the natural slope and vegetation.
Another method for generating a topographic map is that which is same as what we have done in practical 1. In practical 1, we need to use stereoscope to calculate some date which is the x, y, z value of the photo. As topographic map means that we use these values to produce.
The disadvantage of this method is that it needs to input and calculate all the data manually. However, StereoMapper is a computer program and we do all the process on the computer, we can output the data file to be ascii or text file and use excel to calculate the result. Also, it may still not a very accurate method when you compare it to analogue instruments which can magnify images and increase stability."
StereoMapper (SMP) is a product from 3DMapper and provides a reasonable environment for stereoscopic digitising. A companion module, StereoMaker (SMK), is used for the IO, EO and epipolar resampling processes required for SMP.
Choosing IO transformations.
I don't know how many times I talk about this with students and still read it in their reports:
"The RMS residuals tell us how accurate the inteior orientation is. The smaller the residuals, the more accurate is the result. In our practical the RMS residuals for the affine transformation is smaller than for the conformal transformation. That means the affine transformation more accurately describes the distortion of the photo. The residuals for the projective transformation are zero because there is no redundancy when there's only four fiducial marks. We cannot use the projective transformation because we cannot find any errors."
What's the problem with this type of argument?
I need some advice. How would you deal with this?:
"StereoMapper actually is the digital version of stereoplotter, taking topographic features from air photos. What it differs is its medium. On the hand, Aerial Photogrammetry extracts such kind of features directly from aircraft.
In general, StereoMapper is more convenient because we cannot always employ aircraft to film a region. Instead, we only need sit in front of computer and digitize the features we are longing for. It implies we can produce a topographic map whether it is stormy and sunny.
Also, the StereoMapper allows us to examine features very closely (to zoom in and out) so that we can collect and process image quite accurately. In contrast, aerial photos give us only an overview of the region although its quality is not bad. Its focus is fixed so that we cannot see its details accurately.
The most important thing is once we get aerial photos we have to do plainmetric mapping ourselves including radial triangulation and resection. This involves accurate hand and patient in order to map some features for only a region for a considerable time. Even mosaics and orthoimages, which are also photogrammetric products, need complex mathematical model to rectify photos and maintain their geometric relationship. But those vigorous calculation and photo rectification are absent in StereoMapper with just digitizing features that make up a topographic map.
Sometimes, it is not so advantageous to use stereo photogrammetry as features and sites change frequently because of new construction site and building projects. These change the landscape of a region. So we need to have aerial photos to tell us how change has been undertaken e.g. the effects of new buildings/roads upon the natural slope and vegetation.
Another method for generating a topographic map is that which is same as what we have done in practical 1. In practical 1, we need to use stereoscope to calculate some date which is the x, y, z value of the photo. As topographic map means that we use these values to produce.
The disadvantage of this method is that it needs to input and calculate all the data manually. However, StereoMapper is a computer program and we do all the process on the computer, we can output the data file to be ascii or text file and use excel to calculate the result. Also, it may still not a very accurate method when you compare it to analogue instruments which can magnify images and increase stability."
StereoMapper (SMP) is a product from 3DMapper and provides a reasonable environment for stereoscopic digitising. A companion module, StereoMaker (SMK), is used for the IO, EO and epipolar resampling processes required for SMP.
Choosing IO transformations.
I don't know how many times I talk about this with students and still read it in their reports:
"The RMS residuals tell us how accurate the inteior orientation is. The smaller the residuals, the more accurate is the result. In our practical the RMS residuals for the affine transformation is smaller than for the conformal transformation. That means the affine transformation more accurately describes the distortion of the photo. The residuals for the projective transformation are zero because there is no redundancy when there's only four fiducial marks. We cannot use the projective transformation because we cannot find any errors."
What's the problem with this type of argument?
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