Messages

1

General / Re: Modeling vegetation

« on: May 02, 2015, 12:53:10 AM »

Thanks for the reply.  How about just getting overall form of the vegetation?

2

General / Re: Export Textured View with Cameras Floating Above

« on: May 01, 2015, 10:21:15 PM »

Thanks James - this helps. 

Seems like it might be handy for Agisoft to add an "export current view" option or something similar.

3

General / Modeling vegetation

« on: May 01, 2015, 10:17:13 PM »

Do I stand a chance in modeling the vegetation included in the below Agisoft screenshot?  I have produced a dense cloud on "high" but there is not enough feature matching occurring in the canopy. 

I know there are other posts on modeling vegetation;  I'd simply like someone to give me indication whether or not it is at all possible to produce a good-looking model of the scene, or if the veg structure is simply too complicated and shadowed. I've also included the info from the chunk so that you can advise me if I should change settings. I'm also only showing one of my flight lines in the screenshot.  I should also note that I've tried depth filter mode on mild and it hasn't helped much.

4

General / Export Textured View with Cameras Floating Above

« on: May 01, 2015, 02:28:28 AM »

Is there any way to export a view of my model with the blue camera positions hovering above it?   I could take a screenshot but would like something with higher resolution.

5

General / Re: Model looks great, but DEM is rotated on export

« on: March 02, 2015, 08:47:11 PM »

Here's my dilemma.  I want to get this thing exported as a top-down DEM.  However, the only known points of elevation in the scene are on the grassy side.  If I add GCPs on that side with proper Z values, it significantly warps the rest of the scene.  And, I assume there's no way to enter GCPs without Z values.

So, is there any way to simply transform the point cloud in Agisoft to be nadir view of the scene?  Or, any other ideas given the information I've laid out?

6

General / Re: Model looks great, but DEM is rotated on export

« on: February 25, 2015, 01:27:24 AM »

Also - why exactly does it rotate and flip upon exporting?  I still don't quite understand given that it's properly oriented on the ground plane in Agisoft.

7

General / Re: Model looks great, but DEM is rotated on export

« on: February 24, 2015, 06:50:59 PM »

Hi Alexey,

Well I do have I have X,Y, and Z camera positions.  But it seems my DJI phantom 2 vision plus - which others on this forum have warned me doesn't have a great GPS refresh rate - is capturing the same GPS reading for every picture.  I'm attaching a screenshot of the camera positions. 

Is it safe to assume that this fact alone is enough to rotate this model on the wrong coordinate system axis?

8

General / Model looks great, but DEM is rotated on export

« on: February 23, 2015, 09:07:08 PM »

I'm wondering if anyone can give me a simple explanation of why my DEM is coming out rotated.  The model looks great in Agisoft but I can't get it to export with the proper orientation.  I've attached screenshots of the model & DEM.

I'm assuming my problems are stemming from a lack of GCP's (which weren't collected) but isn't there some way I can force the model to export with the same ground plane as is shown in the model?

I'm also including a link to a similar post below, but in that link, the poster's problem seems to be due to having a single flight-line. My flight isn't really a single-line, but perhaps it is close enough to a single line that it's resulting in the same problem.

http://www.agisoft.com/forum/index.php?topic=1640.0

9

General / Re: Do I need GCPs to get an accurate DEM?

« on: February 19, 2015, 08:39:34 PM »

These responses are very helpful, thanks so much.

So, if the cost of an RTK GPS unit is too prohibitive for my project, am I out of luck? 

Or, is there some way to do this without an RTK if I don't need absolute elevation above sea level, but rather am content with assessing relative change in the scene between two time points?  In other words, what if I ditch the hopes of getting this thing geo-referenced, and instead just focus on elevational changes in the scene? I'm assuming I still need a unit of some sort to truth things, but thought I'd check with you all to confirm.

10

General / Re: Do I need GCPs to get an accurate DEM?

« on: February 15, 2015, 10:39:30 PM »

Ok, and I need to obtain elevation at each GCP, not just lat/lon - is that correct?

Also, will it significantly warp things if I don't have a GCP in the middle of the scene?

11

General / Re: Do I need GCPs to get an accurate DEM?

« on: February 12, 2015, 10:31:09 PM »

Thanks for all the responses.

Ideally, I'd like to detect changes in elevation of <1 foot.  Since the scene is highly dynamic, I'll be shooting frequently.

If you have a chance, please take a look at the attachment.  It shows the scene at two time points.  The red line is meant to indicate - albeit roughly - where elevation is relatively constant.  The dirt formation in the middle is what's changing (sediment from a nearby river is being added to the formation).  The width of the scene is ~280 meters.

So, I think I'm hearing that I need to invest in another piece of equipment that can get accurate measures of X, Y (and Z?) at various locations throughout the site. Is this right? Also, any suggestions on how to lay out the GCPs given the dynamic inner portion of the scene and the consistent edges?

I'm new to all of this, so thanks for bearing with me!

 

12

General / Do I need GCPs to get an accurate DEM?

« on: February 12, 2015, 03:39:22 AM »

I'm shooting with a DJI phantom vision 2 plus.  I shoot in RAW so I get GPS coordinates and altitude with each photo. 

My question seems simple: do I need GCP's to ensure accurate elevation and georeferencing? My initial outputs would seem to suggest so, but I'm looking for confirmation.  I'm able to compare the DEM outputs from Agisoft against a high-resolution lidar-based DEM.

The site is under transformation and I'd like to detect small-scale elevation changes.

13

General / Recommendations for aerial shooting of a dynamic scene?

« on: February 09, 2015, 09:03:19 PM »

My goal is to shoot a site frequently enough to detect very small-scale landscape changes. I am looking to create very accurate DEMs, within a foot accuracy if possible.  I'm particularly interested in what's changing inside of the scene - the only consistency in elevation is on the outside of the scene (see the attached photo which consists of the scene at two different time points). The width of the scene is about 265 meters/870 feet.

I'm looking for recommendations on how to shoot this site, e.g.:
1. how many flight lines?
2. what altitude for flying?
3. do I need GCPs? If so, how do I go about creating them, considering the consistency is on the edge of the scene?
4. anything else that will help yield extremely accurate DEMs.

Also, I'm shooting with a DJI phantom vision 2 plus.

Thanks!