new question --> use of parametes

src/content/docs/tutorials/options-selection-guide.md

@@ -16,16 +16,44 @@ Please note: this guide is not perfect; finding the right parameters is not alwa
 **Recommended setting**
 - `rolling-shutter: true`
 **Why?**
-Rolling shutter sensors introduce geometric distortion when images are captured while the drone is moving.
+Rolling shutter sensors introduce geometric distortion when images are captured while the drone is moving ('doming' effect: the ground appears unnaturally arched).
 **Best practice**
 For future surveys, if possible:
 - reduce the flight speed;
 - use **Stop-and-Hover** mode when taking photographs.
 
+
+## Rolling-shutter is on but you notice 'doming' effects (where the ground appears unnaturally arched) and want to maximize the precision of the camera positioning?
+
+ Enable use-hybrid-bundle-adjustment. This increases the frequency of global and local optimization cycles during the SFM phase
+
+## Do you have a pre-existing, precise calibration file for your lens?
+
+Enable use-fixed-camera-params. This prevents the software from attempting to auto-calibrate the optical parameters 
+
+
+## Are you using a multispectral or thermal sensor (e.g., for precision agriculture or temperature analysis)?
+### if yes
+
+Note: read [Multispectral and Thermal section] (multispectral.md)
+
+#### Output Analysis
+
+Once the process is complete, use the "Plant Health" tab in the map view to apply algorithms like NDVI, or the "Thermal" tab to view heat maps.
+
+
 ---
 
 # Step 2 - Survey Characteristics
 
+## Do you want the software to automatically restrict the reconstruction to the specific perimeter where the drone photos were taken, avoiding unnecessary background processing?
+
+### If yes
+Enable auto-boundary. This creates a polygon around camera positions to limit the reconstruction area. You can refine the width of this boundary using auto-boundary-distance
+```text
+auto-boundary: true
+```
+
 ## Do the images include the sky or horizon?
 ### If yes
 **Recommended setting**
@@ -40,8 +68,36 @@ sky-removal: true
 ## For close-range object reconstruction
 Use:
 ```text
-bg-removal
+bg-removal:true
 ```
+
+## Are you processing image frames extracted from a video file?
+
+### Video Parameters
+- video-limit: Defines the maximum number of frames to extract from the video. The default value is 500. Increasing this value can improve coverage, but it also proportionally increases processing time and memory (RAM) usage.
+- video-resolution: Sets the resolution (in pixels) of the extracted frames. For example, if a 4K video (3840×2160) is processed with this parameter set to 2000, the extracted frames will have a resolution of 2000×1125 pixels.
+###  Matching Optimization
+matcher-order: Perform image matching with the nearest N images based on image filename order. Can speed up processing of sequential images, such as those extracted from video. It is applied only on non-georeferenced datasets. 
+
+This is a key parameter when processing videos. Since the extracted frames are sequential, forcing the software to match images based only on their temporal order (for example, by setting a  low value of 10 or 20) prevents every frame from being compared with all the others, saving hours of unnecessary computation.
+
+### Geolocation (GPS) 
+**'.srt' File**: If you are using a DJI drone, the video is often accompanied by a subtitle file with the **same name** (for example, video.mp4 and video.srt). If you upload both files, WebODM will use the .srt file to extract GPS data and correctly associate it with the extracted frames.
+
+## Important Notes
+- Resize Images: The standard Resize Images option available in the task settings does not affect video files. To reduce the size of the frames extracted from a video, you must use the video-resolution parameter described above.
+
+- Quality: WebODM automatically filters out frames that are too dark or blurry during extraction to improve the quality of the final reconstruction.
+- Restart: If you change video-limit or video-resolution and want to restart the processing workflow, you will need to start again from the Load Dataset stage.
+
+- If you need to display the video on the map as supporting documentation (without processing it for photogrammetry), you can upload it using the Media button associated with an existing completed task
+
+
+
+
+
+
+
 ---
 # Step 3 - Surveyed Scene
 ## Does the area contain vegetation or low-texture surfaces?
@@ -75,6 +131,8 @@ pc-quality: high
 - Better reconstruction of vertical walls
 - Sharper building edges
 
+
+
 ---
 
 # Step 4 - Ground Sampling Distance (GSD)
@@ -111,7 +169,12 @@ If increasing this value, also increase:
 ```text
 mesh-size
 ```
+
 to avoid excessive mesh simplification.
+
+### Do you need a 3D mesh that is geometrically complete even in areas 'unseen' by the cameras (closed faces without color)?
+Enable `texturing-keep-unseen-faces`.
+
 ---
 
 ## Priority: Digital Terrain Model (DTM)
@@ -126,8 +189,21 @@ Adjust these parameters:
 | `smrf-slope` | 0.1 for flat terrain, up to 1.2 for mountainous terrain |
 | `smrf-threshold` | Minimum object height to remove |
 
+### Do you have an extremely dense point cloud and want to speed up DSM/DTM generation by simplifying the source data?
+Use `dem-decimation`. For example, a value of 50 tells the software to use only 2% of the points, significantly reducing file writing times
+
+### Does your orthophoto or DEM have jagged edges or 'dragging' artifacts at the borders that you want to trim away cleanly?
+
+ Set the `crop` parameter (in meters) to shrink the final boundary and remove interpolation artifacts.
+
+### Does your terrain model have 'holes' (areas without data) that you want to fill more accurately using multiple interpolation passes?
+
+Increase the `dem-gapfill-steps` to control the number of iterations the algorithm uses to fill empty cells.
+
 ---
 
+
+
 ## Priority: Fast Processing
 Enable:
 ```text
@@ -311,9 +387,9 @@ This generates optimized 3D Tiles suitable for web streaming.
 
 ---
 
-# Step 7 - Accuracy Verification
+# Step 7 - Accuracy Verification / Alignment and Multitemporal Surveys
 
-## Are Ground Control Points (GCPs) available?
+##  Are Ground Control Points (GCPs) available?
 
 To obtain an independent accuracy assessment:
 
@@ -330,6 +406,11 @@ Checkpoint observations:
 - are used exclusively to compute independent accuracy statistics in the **Quality Report**.
 
 
+## Are you conducting a follow-up survey of an area processed previously, and do you need the new model (point cloud or DTM) to align perfectly with the old one?
+
+    Action: Use the align parameter. In the WebODM interface, select the reference task from the "Alignment" field. This instructs the software to ignore the original GPS/GCP data of the new survey and anchor it geometrically to the existing reconstruction.
+
+
 
 ---