Topics

1

General / DEM Hillshade editing

« on: May 09, 2017, 06:17:19 PM »

Hi,

Is it possible to edit the scale on the Hillshade view?
Can we change the lowest and highest elevation or set classes?

Thanks
Miguel

2

General / Exported Orthophoto mixes up coordinates

« on: June 26, 2015, 12:54:41 PM »

Hi guys,

I'm trying to export a DEM or Orthophoto into Arcmap so I can create a raster that colours everything below 5m elevation into blue (for example) simulating a flooding event.

I'm using in Arcmap: ArcToolbox --> Spatial Analysis tools --> Map Algebra --> Raster Calculator
Then, I click twice on my DEM on the layer's box to get it into the console and then I add: <= 5  and press enter. Done!
If everything works out I'll have something like in the attached image: "printscreen of success"

The issues I'm having are:

If I export the DEM in a tiff file with projections plane defined as : TopXY everything works out Ok and I can do what's described above in Arcmap.

However, if I try to export a DEM with the projection plane as "current view" (which gives me a custom view of the model) then the coordinates come all funky. Instead of the DEM having an elevation range from 0 to about 15m it shows as 0 to 250 or something crazy, and some elevations get crazy measures that make no sense.

Also:
If I export as an Orthophoto, even if I choose a projection plane defined as : TopXY the same issue happens as described above.

Here's the project's link in dropbox:

https://www.dropbox.com/s/p08wwj8yox2jsx7/Mto%20Altas%20depois%20de%20dense%20cloud.psz?dl=0


Can anyone help? Is this a bug or I'm I just doing things wrong?

Cheers
Miguel

3

General / High accuracy without GPS

« on: February 11, 2015, 06:07:13 PM »

Hi,

Anyone knows if it's possible to get a terrain model with high elevation accuracy (around 15 centimetres/ 6 inches) without using a GPS? I don't need to locate the model geographically, just the elevation within the terrain.

I was told that If I use several GCP's  spread along the terrain and know the exact measure between them and their elevation difference between them, I can get a very good accuracy.

Anyone tried something similar or has any better idea to achieve this?

Thanks for your help
Miguel

4

General / GoPro with modified lens for high accuracy DEM

« on: February 05, 2015, 05:08:27 PM »

Hi,

For my project I need to "see" the elevation of a beach to an accuracy of 10cms or less.
Since I don't have much money for this, I was thinking about buying the Phantom 2 and GoPro with Gimbal, PFV and pre set flight patern since this is a cheap all in one setup.

Then I saw that the GoPro is an issue because of the too wide angle lens and the rolling shutter, so I tried to find another solution until I saw this tread by Porly:
http://www.agisoft.com/forum/index.php?topic=2480.0

He says that with a modified lens to 60ª he saw no difference from a professional setup, except the quality of the orthophoto, but that the cloud point was no different.

Anyone has good experiences with a modified GOPro for accurate height calculations?

Cheers

5

General / How to mount an external camera on a Phantom 2 ?

« on: January 22, 2015, 03:32:42 PM »

Hi,

I'm thinking of buying the Phantom 2 and use a compact camera since the Gopro or the built in cameras from DJI have all too wide angles and rolling shutters.
I pretend to take advantage of the DJI phantom 2 capability to have pre set up flight paths.

Problem is I can't find any gibles for other cameras besides the GoPro. All gibles models on the DJI website are for the GoPro or for older DJI copter models.
How are you guys doing it to use the phantom 2 and other cameras besides the GoPro?

Is there any other cheap equipment combination beside this one?

Are you using a live view of the flight  as well? is this important?
I'm planning to take photos at about 30 meters high as I need a good elevation resolution around 10cm accuracy.

Thanks!

6

General / realign a subset of photos

« on: October 28, 2014, 03:31:21 AM »

Hi,

On Agisoft manual is says:

“…To see the matches between any two photos use View Matches command from a photo context menu in the Photos pane. Incorrectly positioned photos can be realigned.

To realign a subset of photos
1. Reset alignment for incorrectly positioned cameras using Reset Camera Alignment command from
the photo context menu.”

So, on the “view matches” how can I know if they are well aligned or not?

What does these values there mean? I can see a column saying “Total”, “valid”,”invalid” and 2 photos full of red and blue lines…
How can I use this info to understand if a photo is incorrectly positioned?

Is there anywhere I can understand this better? Any detailed tutorial on this? Can anyone help?

Thanks!

7

General / How to measure elevation on specific terrain points

« on: September 15, 2014, 03:46:57 AM »

Hi,

I'm trying to use Photoscan pro to create a DEM of a beach and then measure the elevation at different points in the terrain. The idea is to get turtle nest's coordinates and populate the DEM from photoscan with those coordinates and them measure the elevation of each nest.

Is this possible at all, I mean is photoscan DEM elevation accurate (less than 15cm error)?
Do I have to import the Photoscan beach DEM to ArcGIG and do it there?
And if so, is there any specific tool in GIS for this?

Sorry for so many questions at once. All help or online tutorials/manuals on this particular issue would also be much appreciated.

Thanks!

8

General / Mesh upside down

« on: July 29, 2014, 07:52:08 PM »

Hi,

I'm using the pro version. After importing all the photos, doing the dense cloud and mesh, everything looks great except the model is upside down, like if the photos were taken from below the ground instead of from above.
I didn't enter any GPS coordinates into any of the photos, however they are well aligned everywhere except for the fact that everything appears flipped vertically.

Can anyone help me out?

Here's the project's mesh:
http://we.tl/RmFyewehi7